Common Words:
* La: The (feminine)
* Las: The (feminine plural)
* Le: Him/her/you (formal singular, indirect object pronoun)
* Les: Them/you (plural, indirect object pronoun)
* Lápiz: Pencil
* Libro: Book
* Luna: Moon
* Lugar: Place
* Llave: Key
* Leche: Milk
* Llegar: To arrive
* Leer: To read
* Listo: Ready
* Llama: Llama (animal)
* Luz: Light
Less Common, but Useful Words:
* Largo: Long
* Lento: Slow
* Línea: Line
* Lluvia: Rain
* Llamada: Call (phone call)
* Limpiar: To clean
* Loco: Crazy
* Llano: Plain (flat land)
* Letra: Letter (of the alphabet)
* Libre: Free
More Advanced/Specific Words:
* Laberinto: Labyrinth
* Laboratorio: Laboratory
* Legislación: Legislation
* Literatura: Literature
* Llanura: Plain (flat land, more formal)
* Licencia: License
* Lograr: To achieve
This is just a small sample, as many more words begin with "L" in Spanish. The frequency of use will vary depending on the context.