Yes, but it does not mean the same thing. Your sentence "de kan svenska" just means that they know how to speak Swedish, whereas the sentence here means either that OR that they speak Swedish as in what they're currently doing.
"Talar" is a bit more formal. Also, if you are a speaker of a language, "talar" is more common to use, but if you are talking right now, it's more common to use "pratar". So, yes: talar - speaks; pratar - talks