This is the 454th most frequent Chinese word.
雖然
"Although" or "though."
In this sentence, "雖然" is used as a conjunction to introduce a clause that describes a condition or background (it rained today) that contrasts with the main clause (we still went for a picnic).
雖然今天下雨，我們還是去野餐了。
Although it rained today, we still went for a picnic.
Here, "雖然" connects the clause describing a limitation (I haven't studied for long) with one that contrasts it (I can answer basic questions).
我學中文不久，雖然，我可以回答基本問題。
I haven't been studying Chinese for long, however, I can answer basic questions.
In this example, "雖然" introduces the background condition (he is busy) that contrasts the following action (he visited me).