This is a console command that lets you bind other console commands to a key.
bind <key> <command(s)>
Example: If you wanted to make the V key toggle noclipping, you would type in console:
bind v "noclip"
Example: If you wanted to make the H key make you say "Hello." in chat, you would type in console:
bind h "say Hello."
Example: If you wanted to make the L key prepare your screen for screenshots, you would type in console:
bind l "cl_drawhud 0;crosshair 0;impulse 200"
Quotation marks around strings are not always required, but should be used to ensure that special characters, such as spaces and semicolons, are not misinterpreted. For number-only strings, quotation marks should not be used.