I have to be honest. I am not very familiar with either of these two teams. However, Angola looks to be like a much better side. Mauritania has a -3 goal difference after the first game, whereas Angola drew with Tunisia, one of the better teams in the group. Before this game, they won 3. Meanwhile, Mauritania is on a 3 loss streak, and their opponents are not what you can consider top-tier teams.
Angola will look to reach the knockout stage, and this game should be a walk in the park for them.