Installing a src.rpm is very much like unpacking the source code of a program. If you run (as yourself) :
rpm -vv -Uvh package.src.rpm
You will see the source installed under your home under a rpm tree:
rpm/SOURCES
rpm/SPECS
You will find a spec file telling how the rpm is built. You will find one or more files needed to build the RPM under the SOURCES directory.
You will also see
rpm/BUILD
rpm/RPMS
rpm/RPMS/i386
rpm/RPMS/i686
...
The BUILD dir is used when the rpm is rebuilt. The final RPM gets written under the appropriate RPMS subdirectory.
The interest of installing a src.rpm is to modify and rebuild it. But if the source you need already contains spec file to build the rpm, it's better downloading the source and building the rpm from it when you so desire:
rpmbuild --rebuild -bb rpm.spec
You can find more information on rebuilding srpms here: How to unpack and rebuild RPM packages on Fedora?How to unpack and rebuild RPM packages on Fedora?
