5月用英语来说怎么说

"May" is the Engpsh word for the fifth month of the year. So you can simply say "May" to refer to the fifth month in Engpsh.

For example:

"I was born in May." (This means that the person was born in the fifth month of the year.)

"The flowers usually start blooming in May." (This means that the flowers usually start blooming in the fifth month of the year.)