How to tone muscles?

I am brand new to working out. I’m happy with my weight, I’m just looking to tone my body (flatten stomach, tone legs, back, and butt). My husband told me I shouldn’t just work on those muscles everyday because it’ll end up not helping me as much which confused me. So now I feel like I have no idea what I’m doing. I thought the more you work on those muscles, the stronger they get. Please help!