「結婚する」 (kekkon suru) means "to marry" or "to get married." It describes the act of two people becoming husband and wife. You can use it to talk about future plans or past events, often with the particle 「と」 for who you marry. For example, 「来年、結婚します。」 (I will get married next year.)

「結(けっ)婚(こん)する」は、夫(ふう)婦(ふ)になることです。来(らい)年(ねん)、結(けっ)婚(こん)します。