Questions & Answers about Bugun yana da ƙarfi.
Because Hausa normally keeps an agreeing subject marker before the predicate, even when you already name the subject.
So the structure is roughly:
Bugun + yana + da ƙarfi
Here, Bugun names the subject, and yana agrees with it before the rest of the sentence. English does not do this, but Hausa often does.
Because bugun is treated as a masculine singular noun in Hausa, so it takes the masculine agreement form yana.
A very important point for English speakers: Hausa agreement is based on grammatical gender, not just natural gender. So even things that are not people can be grammatically masculine or feminine.
If the noun were feminine singular, you would expect tana instead.