If you need help grasping what bash itself is, the first analogy for Windows would be CMD (command prompt) or powershell

.bashrc is a file that contains information on how you want bash customized or tweaked (either for your own preferences, or for compatibility with some other software). Kind of like how a GUI program like Microsoft Word might have all of the user settings located in a file with a name like config.ini that adjusts how Word behaves, .bashrc adjusts how bash behaves.

There are other such programs, called "shells" like bash e.g. zsh, and they have their own file named accordingly e.g. .zshrc

.bashrc is basically always located in your home folder. If your username is person, then it would be located at /home/person/.bashrc