强(qiáng) - strong, powerful; better than in Mandarin

强 (qiáng) is strong in the sense of capability and power: a strong team, a strong wind, a strong memory. Its opposite is 弱 (ruò, weak). For physical strength in the arm you usually want 有力 or 力气大 instead.

It also does comparison work that English handles with "better". 这个队比我们强 means this team is better than us, not merely more muscular, and 能力很强 means highly capable. That second use is everywhere in job adverts and school reports.

Two things to keep separate. 强 is not 墙 (qiáng, wall), which sounds identical, and it has a second reading qiǎng meaning to force, as in 勉强 and 强迫. It is also the base of the compounds 强大 (mighty), 加强 (to strengthen) and 坚强 (resilient in character), the last of which is about the mind rather than the body.