The command for Insert mode abbreviations looks like this:

:iabbrev [<expr>] [<buffer>] {abbreviation} {expansion}

• - stands for Vimscript expression to create the expansion.
• - means that it only applies to the current buffer.
• {abbreviation} - is the thing you type, or your “trigger”
• {expansion} - is your final outcome
• Anything that’s inside a [] is optional.