The Spanish word como (an adverb but also a conjunction) has many different meanings. Let's explore a few examples to learn how to properly use it.
 
Generally speaking, the adverb como has a comparative meaning. You can use it with the verb ser (to be) to compare things, people, actions, etc. There are different ways in which this como can be used, but it usually translates as "as" or "like."

BANNER PLACEHOLDER 

Nadie como tú me llena

No one fulfills me like you

Caption 18, Michael Stuart - Me Siento Vivo

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Yo tenía cuidado de no pisarlas como tú me enseñaste.

I was careful not to step on them as you taught me.

Caption 33, Guillermina y Candelario - La Isla de las Serpientes

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But the adverb como can also mean “about” and be used to make an estimate, or approximation (which in a way is also a comparison).
For example, to estimate an amount of money:

Que esto ya cuesta como veinticinco soles.

This alone already costs about twenty-five soles.

Caption 41, Cocinas Peruanas - Short Film

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Or to estimate an amount of time:

Estos muslitos se van a tardar como unos quince, veinte minutos.

These little thighs are going to take about fifteen, twenty minutes.

Caption 15, [Bears in the Kitchen] Osos en la cocina - Pollo asiático

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On the other hand, as a conjunction, the word como has even more uses, equally interesting. For now, let's just study the most common ones: como meaning "as" or "since" and como meaning "if."
 
When the conjunction como is used to establish an antecedent condition it means "as" or "since:"

Como ya les dije,

As I already told you,

Caption 26, Lecciones de guitarra - Con Cristhian

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Y también como sos uruguaya,

And also since you are Uruguayan

Caption 62, Biografía - Natalia Oreiro

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The conjunction como can also be used in a conditional clause that translates as an "if" clause. It's used with the subjunctive, it's not very common, and it's typically used to make threats or prevent people from doing or not doing something:
 

Como no vengas le digo todo a mamá.
If you don't come I'd tell mom everything.

Como no me hagas caso, lo pasarás mal
if you don't listen to me, there will be trouble

BANNER PLACEHOLDER

As you can see, this como is more commonly used in the negative form. And, by the way, it's just an alternative to using a si clause (which doesn't need the subjunctive):

Si no vienes le digo todo a mamá.
If you don't come I'll tell mom everything.
 
Si no me haces caso, lo pasarás mal
if you don't listen to me, there will be trouble