있다 is a Korean verb which literally means to exist, although this often is used to show possession (i.e., to have something) though it technically doesn't take any direct objects-meaning you cannot quite use it like you would in English with the verb "to have". In any case, you will also see it appear in various forms based on speech register/level of politeness or humility. The three most common for survial purposes are:
있다 (dictionary form/very informal)
있어 (informal)
있어요 (formal, generic politeness)
You will likely use 있어요 for the vast majority of your communication in Korean.
Survival Korean
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Survival Korean