Learn how to install COBOL locally to solve Exercism's exercises on your own machine
Unlike newer languages, COBOL has multiple well-maintained compilers, though each has their own benefits.
GnuCOBOL is the Free Software Foundation's Free and Open Source COBOL Compiler. It transpiles COBOL into a C program before using GCC to compile that into an executable. Instructions for installation can be found here.
As a mainframe vendor, IBM maintains its own dialect of COBOL that works on its z/OS as well as other modern operating systems. IBM COBOL can be obtained free of charge through applying for the COBOL environment for VSCode, which is part of the Open Mainframe Project.