According to Scitable, a human fetus briefly has a tail, but as Wikipedia explains, it doesn’t have gills during any stage of development. The pharyngeal arches, which are colloquially referred to as gill slits, have no relation to functional gills found in fish.
During human fetus development, six pharyngeal arches develop, each with its own artery, nerve and skeletal tissue. However, the fifth arch only exists for a short period, Wikipedia further explains.
Scitable notes that the fetal tail disappears before the baby is born, similar to the fifth pharyngeal arch. However, if the Wnt-3a gene regulation is impaired, there is a very slight chance for a baby to have an actual tail after the birth, according to Scitable.