The verb to know has two Spanish equivalents: saber and conocer.

Saber is used only for information, something you cannot touch. Conocer, on the contrary, is used for physical objects (including people).

Thus,

Sé dónde vives – I know where you live (information)
Conozco tu casa – I know your house (I can visually recognize it)
Conozco Madrid – I know Madrid (I know my way around)

Sé inglés, sé muchas canciones de los Beatles – I know English (information), I know a lot of The Beatles songs (information: words and music)
Conozco a un chico inglés, conozco los Beatles –  I know one English guy (an object of the physical word), I know The Beatles (people who can be recognized in the photo)

You can only use the verb saber with the following infinitive in the meaning “can do something well":

Sé cocinar – I can cook, I cook well

On a more advanced level, it is good to know there is a verb saberse, meaning "know something by heart":

Me sé un poema – I know a poem by heart
Juan se sabe un truco de magia estupendo – Juan knows a great magic trick (he knows the sequence of actions by heart)

It should be mentioned that some nouns can be regarded as both objects and information, in this case they can be used with both verbs though with slightly different meanings:

Sé esta canción – I know (very well, probably by heart) this song
Conozco esta canción – I know this song (I’m familiar with it, I recognize the melody, though I may not know the words)

Sé una buena receta – I know a good recipe (information), I can easily repeat it
Conozco una buena receta – I know a good recipe (the text in the cookery book) though I may not repeat it offhand

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