The Spanish llamar (to name; commonly used to say “My name is”: “Me llamo” is literally, “I call myself…”) comes from the Latin clamare, meaning “to cry out, shout, proclaim.”
This is an example of the pattern where Latin words beginning in “Cl” are changed to the double-l (“ll”) in Spanish. In English, these words retain the “cl” sound – from the same root we get claim and clamor.
Other examples of this pattern include llave and clef.
The Latin words that began with “cl” changed, pretty consistently, to “ll” as Latin changed into Spanish.
Today’s example of this: the Latin word for “key” was clavis. This became the modern Spanish word for “key”, llave.
There are, however, a few interesting other descendants of clavis, and thus distant relatives of llave. They include: