This is the 4472nd most frequent Arabic word.
وغالبا
"Mostly" or "often".
The word "وغالبا" is used to introduce a common occurrence or tendency, which in this sentence emphasizes the frequent behavior of children playing after school.
وغالبا ما يقضي الأطفال أوقاتهم في اللعب بعد المدرسة.
And often children spend their time playing after school.
The term "وغالبا" here is applied to express a regular phenomenon seen, where long shadows are observed in the morning.
وغالبا ما تجد الظلال الطويلة في الصباح.
And often you find long shadows in the morning.
In this context, "وغالبا" highlights a probable reason or frequent cause for Ahmed's absence, making the statement informative about his usual reasons for not attending.