Noether's theorem holds in quantum mechanics and in classical mechanics. Noether's theorem sounds like magic when you first hear of it: to help put it on solid ground for you, I'll run through the logic of Noether's theorem (from a physicist's perspective) for a single point particle in a potential, so you can get a feel for how it works and what it means.
Take a simple Lagrangian $$L=\frac{1}{2}m\dot{q}^2+V(q).$$
We will show that if the potential $V$ is explicitly time-independent (that is, $\partial_tV=0$) that there is an associated conserved quantity (this will be the energy). The action is defined as $$S=\int\text{d}t\,L=\int\text{d}t\left[\frac{1}{2}m\dot{q}^2+V(q)\right]$$
Let's assume that the action is invariant under a time translation $t'=t+\delta t$. Then, we may write $\delta S=0$, because $\partial_t L=0;$ if the Lagrangian isn't dependent on time, then the action shouldn't care about a redefinition of the time coordinate by an infinitesimal constant. We may then write
\begin{align*}
\delta S&=0 \\
&=\int\delta (\mathrm{d}t\,L)\\
&=\int \text{d}t\left(\partial_t\delta t+\text{t} \delta L\right)\\
&=\int \text{d}t\, \delta L,
\end{align*}
We do a standard change of variables to compute the change in $\text{d}t$, but since we are varying by a constant, that change is zero.
The general variation of the Lagrangian follows from the usual chain rule: $$\delta L=L'\delta t+ \frac{\partial L}{\partial q}\delta q+ \frac{\partial L}{\partial q'}\delta q',\,f':=\frac{\partial L}{\partial t}.$$
Don't get tripped up! The dot on $q$ in the Lagrangian is a total time derivative, while our prime notation denotes a partial one. Using the Euler-Lagrange equations, we may write
\begin{align*}
\delta L &= \frac{\partial L}{\partial q}\delta q + \frac{\partial}{\partial t}\left(\frac{\partial L}{\partial q'}\delta q\right)-\frac{\partial}{\partial t}\left(\frac{\partial L}{\partial q'}\right)\delta q\\
&=_\text{on-shell}\underbrace{\left[\frac{\partial L}{\partial q}-\frac{\partial}{\partial t}\left(\frac{\partial L}{\partial q'}\right)\right]}_{=0}\delta q+ \frac{\partial}{\partial t}\left(\frac{\partial L}{\partial q'}\delta q\right)\\
&=\frac{\partial}{\partial t}\left(\frac{\partial{L}}{\partial \dot{q}}\delta q\right)
\end{align*}
Putting this into the action, we get $$\delta S=\int\text{d}t\frac{\partial}{\partial t}\left(L+\frac{\partial L}{\partial \dot{q}}\delta q\right).$$
Now, the total variation of the position is $$\delta q_T=\delta q+q'\delta t.$$ Under an infinitesimal, constant time translation, $\delta q_T=0$, so we have $\delta q=-\dot{q}\delta t.$ Plugging this in (and remembering that $\delta q$ is a constant, so we can pull it out of the derivative) we get $$0=\delta S=\int\text{d}t\frac{\partial}{\partial t}\left(L- \frac{\partial L}{\partial \dot{q}}\dot{q}\right)\delta t.$$
Since this must hold for arbitrary constant $\delta t$, we have $$\boxed{E=\frac{\partial L}{\partial \dot{q}}\dot{q}-L,}$$
where $E$ is some constant. For our Lagrangian, we have
\begin{align*}
E&=m\dot{q}^2-\frac{1}{2}m\dot{q}^2+V(q)\\
&=\frac{1}{2}m\dot{q}^2+V(q)
,\end{align*}
the total energy.
This is the substance of Noether's theorem: a symmetry of the action leads to a conserved quantity. The generalization to classical field theory is easy, because classical mechanics is just a one-dimensional classical field theory. Instead of $q(t)$, you have $\phi(t,\mathbf{x})$, and you follow a similar set of steps above to find that energy-momentum is conserved for spacetime translations. This can be carried over to quantum mechanics/field theory fairly easily; the technical details are beyond the scope of this answer.
Note: For internal symmetries of the fields, you can also derive conserved quantities. This is how, for example, electric charge is derived. In our example from classical mechanics, $q$ is the field, and if the system is translationally invariant, you get the momentum. This is peculiar to mechanics; in field theory, position is not a field, but a label on a field, like time for $q(t)$, and momentum conservation is derived in an analogous way as the above.