can any body please tell me what this plant is??

If it's actually a houseplant and not one of the Cordylines someone's decided to keep inside as a houseplant, it's commonly known as ti tree, but is actually a Dracaena marginata and it looks like yours is var. "tricolor" or "Colorama". I mention Cordyline as a possibility because there IS one that looks like this, and Dracaena usually has narrower leaves. So you could work it out by measuring the width of the leaves - if it's Dracaena, I wouldn't expect them to be more than a quarter of an inch, maybe fractionally more, wide, but Cordyline will be a good half to three quarters of an inch wide and the leaves will be stiffer. Dracaena's leaves are quite soft and slightly floppy in comparison. Good luck with it!