What Does Thickened Endometrium Mean?

I am 55 female within the last month I have had bleeding and spoting, they stop and slight bleed for overnight, also have a dull ache on my left side of back, my pelvic ultrasound came back with Uterus is bulky measuring 136cc. No mural masses are present.
There is thickening of the endometrium which measures 17.5mm. No focal polypoidal lesions are seen.

There is an uncomplicaed 30mm cyst in the right ovary. No other ovarian abnormality is detected. The adnexae, iliac fossae and POD are unremarkable.

Comment; There is a bulky uterus with thickening of th endometrium, No other specific pelvic ultrasound abnormality is detected