The lunar month around the month of April in the Julian calendar was called the Eostre-monath. And as the Christian tradition of Easter, which has also fallen in April, arrived in some Germanic-speaking regions, the people named the then-unnamed Christian day after the festival, that is, in English as Easter, and in German as Ostern.
In ancient Anglo-Saxon myth, the goddess Eostre (AKA Ostara) is the personification of the rising sun. In that capacity she is associated with the spring and is considered to be a fertility goddess. She is the friend of all children and to amuse then she changed her pet bird into a rabbit. This rabbit brought forth brightly colored eggs, which the goddess gave to the children as gifts.
Happy Eostre everyone!