"I have water in the glass."
"ho" means "I have". It is the first person conjugation of the verb "avere", which means to have.
Your articles are incorrect here. You put "nello bicchiere" instead of "nel bicchiere". nel is a combination of the words in + il. (Similar to conjunctions in english--how they and are become they're) Nello is a combination of in + lo. The correct article for "bicchiere" is "il", hence why you use nel.