La fecha (the date)
The verb ser is used to give dates:
Hoy es el 20 de mayo.
To expand dates to include years, use the preposition de (of):
Es el 4 de julio de 1776.
On the first day of the month use the ordinal number “el primero” (first) and not “el uno”.
Es el primero de enero de 2020.
Remember that masculine forms of the numbers are always used with dates, and months are not capitalized unless they begin a sentence:
Enero es mi mes favorito.
Also remember, to say “in a certain month” use the preposition en (in):
Voy a Guatemala en abril.
However, to say “on a certain day” / “on certain days” use the definite article el / los:
Me voy el lunes.