I used to weight 120 now I weight 127 can people tell if I gain weight?

Only if you try to pour yourself into really tight jeans and have your spare tire pop out from the tops of the jeans. No, a 7 lb weight gain is not that dramatic to really show.

People notice a weight gain mostly in the face. The cheeks plump out. But seven lbs is not a major weight gain. If you want to lose that, then you have a goal. Make your plan and good luck.