Learn Russian: Ты можешь это сделать?

Мочь (to be able to) is the dictionary form. Because the subject is ты (you, informal), we must conjugate it to match. The verb мочь is a bit irregular and changes its stem in most forms. So you get я могу (I can), but ты можешь (you can).

Why doesn't the verb сделать (to do) change its ending?

When you use a modal verb like мочь (can) or хотеть (to want), only the first verb changes to match the subject. The second verb always stays in its dictionary form (the infinitive). Since можешь is already conjugated for ты, сделать just stays as is!

Why is the word это (this) placed before the verb сделать?

Russian word order is very flexible! You can say Ты можешь это сделать? or Ты можешь сделать это? Both are perfectly correct. Putting short words like это before the infinitive is just a very common and natural-sounding habit for Russian speakers.

I learned that 'to do' is делать. Why does it have an 'с' at the beginning here?