1. The dancers had to stop for a few minutes to take a rest. When they got their second wind, they started to dance again.
2. The candidate took the weekend off from campaigning because he was mentally exhausted. He told reporters that he would be back on the campaign trail after he got his second wind.

The expression suggests that when a person gets out of breath (wind), he/she can get a second one in order to continue. It can be used literally (opt.1) or figuratively (opt.2).