Yes, Mars does have oxygen in its atmosphere. However, the amount of oxygen in the Martian atmosphere is very small compared to the amount of oxygen in the Earth's atmosphere. The Martian atmosphere is composed of about 95% carbon dioxide, with only about 0.13% oxygen. This means that if you were to stand on the surface of Mars, you would only be able to breathe about 1/10th of the oxygen that you would be able to breathe on Earth.