if my cousin has a baby what am i to that baby

If your cousin has a baby, you are that baby's "first cousin once removed." This means you and the baby share a common set of grandparents but are separated by one generation. The "once removed" indicates a difference in generations between you and the baby. Informally, many people simply call this baby their cousin or sometimes use aunt/uncle terms depending on family preference, but technically the relationship is first cousin once removed.