gcc is the GNU compiler collection, originally called GNU C compiler.
gcc is commonly invoked from the command line, like so: gcc [ option | filename ]...
This is correct but, probably means nothing to you, one would normally use gcc like so: gcc [flags] file1 [file2 [file3 ...]] [-o output_file] where file1 file2 etc. are input files, either C source files or pre-compiled object files.
Example: gcc foo1.c foo2.c -o foo
The default executable output filename is a.out. When producing object files, the default output for each input file has the suffix .o .