You usually need to copy the extracted files into the main directory of the game it's for (e.g., Slay the Spire or a similar title).
Right-click the file and select "Extract to SlayReborn v1.2/" . This creates a dedicated folder so files don't clutter your directory. SlayReborn v1.2.rar
If the file asks for a password, check the website where you originally found the link; it is often listed in the post description. You usually need to copy the extracted files