Just as in English, a greeting in Spanish is often supplemented with the question, "how are you" In general, the most common Spanish version of this question is como estas? But in Spanish, as with other languages, there's a huge variation of phrases that you may hear that have a similar meaning.
A very common version of "how are you" in Spanish is "como estas" with "como" meaning "how" and the verb "estar" meaning "to be" in a temporal sense. Pronounced "koh-moh ehs-tahs" with the emphasis on the "koh" and the "tahs." This is an informal variation of the phrase. If you're addressing an elder or want to be more formal, ask "como esta usted?" instead. "Como esta" without the "usted" means, "how is he, she or it doing," depending on the context. This phrases are basically used to address a man or a woman.
Que Tal and Que Hay
You may hear "que tal" in leiu of "como estas?" This is an informal version of how are you by saying "what's up" or "what's going on" in English and is pronounced "kay tall." This phrase is similar to "como estas," but a little more colloquial. Another similar phrase is "que hay." It literally translates to "what is there" but is similar to an informal "what's new" or "what's up" in English.
Other Common Phrases
You'll hear a number of variations on "como estas" based on variations in Spanish languages around the world. Some similar phrases are "como te va," "que haces" and "que pasa," all of which mean "how are you" or "how's it going" and merit the same types of responses. If you're doing well, answer "estoy bien" or "muy bien" for "very well." If you're just okay, you can say "asi asi" or "mas o menos."
In general, folks in any Spanish speaking country will understand variations of phrases like "como estas" and "que hace," but each country and region has subtle variations and differences. In Venezuela, someone may say, "como estas pana" which means "how are you, bro" or "how are you, dude?" In Argentina, the term "che" has a similar meaning and will often be used in conjunction with greetings.