Hello and welcome to HCM,
There are a lot of reasons which can get you whitish spots on the abdomen. Mostly if they are not itchy / raised, it could either be
tinea versicolor (
fungal infection) , early vitiligo, idiopathic
hypomelanosis ( a condition caused due to descruction of melanin producing cells) or post
inflammatory hypopigmentation.
Did you have any other lesion, trauma, preceding this spot, if yes its post inflammatory hypopigmentation and mostly it'll regain its colour gradually.
If it is a little scaly, its tinea versicolor, a fundal infection. Apply 1% terbinafine over the lesion once at night and you'll find it resolving within a couple of weeks.
In case its none of the above, i recommend you to see a
dermatologist and get early vitiligo ruled out, since hypomelanosis is fairly uncommon in young age.
Hope I helped