The verb saber (conjugation) means "to know". It is irregular in the present tense.

The verb saber (to know) is used when we speak of knowing facts, something we know by heart, or when know how to do something. Let's review a few examples:

Yo no sé si María lo conoce.
I don't know if María knows him.

...porque no sabes nadar
...because you don't know how to swim.

No sé preparar ese platillo.
I don't know how to prepare that dish.

Sabemos que es una clase de inglés y que se reúne los lunes y miércoles.
We know it's an English class and that it meets Mondays and Wednesdays.

¿Qué saben ellos de este cuento?
What do they know about this tale?