I had a recent endometrial ablation and was informed my uterus was rather lumpy and the size of a ten week uterus what does this mean?

Difficult to say: Hopefully you're endometrial oblation will control the abnormal bleeding. But a 10 week lumpy uterus may either indicate multiple or a single uterine fibroid or adenomyosis.

May be fibroids: A lumpy uterus is probably due to fibroids or benign tumors of the uterus. They may cause cramping and bleeding. Fibroids are a common indication for a hysterectomy.