Do you eat back calories you burned?

Wondering if this is normal.

Been listening to my boyfriend who is an avid gym goer and has lost a LOT of weight.

He says you should eat back whatever you burn on a deficit.

Say your daily limit is 1000. If you burn 500 cals eat 500 more to reach 1000.

I don’t know how this works as when you use online trackers, doesn’t it count for when you’re working out?

Do I re eat the calories or no?

I’ve had an ‘excess’ of 300-700 every day for the past week even though one of the days I ate 1500.

Any help would be appreciated! I’m just confused and not sure who to listen to