Is is possible to use two filters (one polarizing and one ND) at the same time on a 18-55 kit lens from Canon. I am new to photography and wanted to work with filters. Do you suggest me buy these filters?
The front element of the 18-55 rotates when focusing, which makes using polarizing filters a bit irksome. But other than that, yes, it should work, although using multiple filters on a lens is something that should be avoided as far as possible on general principles because of the added risk of flare, internal reflections, vignetting and other optical nasties.
Be aware that some ND filters, especially the less expensive ones, can product a color cast. What may be a subtle color cast can become quite noticable when stacked with a polarizing filter.
I have found I can stack many ND filters together without any strange effects, but the combination of a polarizing filter with (in my case relatively cheap) ND filters produces a strong cast.
Technically, it is possible, you just have to take care of possible vignetting (darkening of the frames margins). Vignetting is usually noticeable when shooting wide angles (short focal lengths), where the extension of the lens tube (e.g., due to filter stack) creates a "tunnel vision" and shades the outer boundaries of the lens.