はなせますvsはなせました

Hi! I'm new...Before I get to my question, I was being taught Japanese for about 6 months ((2 years ago lol) I already know kana, but not kanji and not a lot of phrases or grammar.
I can't afford lessons so I'm self teaching using Japanese for Busy People, Kanji Power, and Memrise.com
On memrise (And I'm not sure how credible that website is - some insight would be helpful) they give you:
"はなせます" for "(I) can speak"
And
"にほんごを はなします" for "(I) can speak Japanese"

Why is it "はなせます" for "I can speak" but it changes to "はなします" when talking about a specific language?
Thank you in advance! ^.^

Welcome.

First, do you realize that the two terms in your subject line are not the same as the two in the body of your post?

Both the words you ask about come from the verb はなす (to speak)

The verb conjugates to はなします, which is just a more polite version with exactly the same meaning.

It changes to はなせる which means "can speak". The more polite equivalent is はなせます

I don't believe I would use that site if that is an example of the sort of careless and inadequate translation and explanation one can expect to find there.

Memrise appears to be a place where anybody can submit a course. Therefore, you should take
everything on there with caution.

Memrise is just a flash card creation website. I've found it's best used to make your own flash cards based on the lessons from your textbook.

For Kanji I recommend making your own flashcards and "answering" each card by writing out the kanji on a sheet of paper. You'll have to do this over and over and over, but writing kanji helps to form stronger memory bonds than only using visual recognition.