When I read a book I found the words ’Modeh Ani’. But I don’t know what it means. I heard that it's a pray sentence. May I please know it’s correct meaning?

Modeh Ani literally means "I thank" or "I declare" and is the phrase that begins the first prayer of the day upon awakening. The content is one of thanks to G-d for restoring one's soul after a night of sleep. See if you can download portions of the Orthodox Jewish prayerbook in English from the internet.