Can you elaborate on what lens, if any, you have just now?
I'm a great fan of expansion before augmentation.
Sure a 50mm or 40mm is cheap, but a decent budget zoom like the terrific EF-s 55-250 IS onluy costs a little more and may actually be the perfect partner for your existing lens.
In the early days, range is probably more useful a learning tool than duplication.
The 50mm is a bargain, and great at certain things.
It isn't a fantastic video lens as it's got a short throw, narrow, gritty focus ring, and very very shallow depth of field if you use it wide open... you will want to manully focus for video, trust me, and so you will want something a little better.
May I recommend a used Sigma 18-50 f2.8 DC Macro? It's bright, sharp and the focus ring has a longer throw and as the aperture is constant your footage doesn;t darken when you zoom.
Tell us more and we can help you more. You say you are a beginner, so we won't bite. Too hard.