Chemistry ?

Hey all,I'm new to UT,about a month and a half in. Can anyone explain like I'm 5 how chemistry works ?I know what the three dots on a card means,I'm trying to understand if it helps with gameplay ? Because My starting 11 normally just yields a chemistry total of like 16-19.

Also ,the chemistry styles like engine and maestro,when you stack them,do they increase ?Is there a formula,kindly explain like I'm 5 lol