No one knows for certain how April got its name, but it may have come from the Latin word 'aperire' which means 'to open'. April is, after all, the month when in the northern hemisphere buds begin to open and things start to grow again after the winter. Eostre monath or Eastremonath was the Anglo-Saxon name for the month. The name of the Christian Festival of Easter comes from this Anglo-Saxon word. 
April in the Northern Hemisphere is during the spring. The hours of daylight are getting longer, the weather is still cold but getting warmer.
In England two migratory Birds, the cookoo and the swallow arive in April so rural people called April the month of the cookoo and the swallow. The Romans thought April was the special month of their goddess of Love, Venus. Romans held many festivals in her honour in April. 
April in the Southern Hemisphere is during the autumn, days are getting shorter and the weather is getting colder.