In addition to Utsu's answer. When we talk about the languages we are learning / we learned, we generally say "I CAN speak ... a little" but "I speak ... a little", it sounds a bit unnatural, at least to me. I would say "I speak..." for my native language, however, there isn't any specific rules. One more thing, the particle を is used after the object but there are exceptions. In this case, it's used with the potencial verb/form, so we use が though in colloquial, を is acceptable. After all, we say: 日本語が少し話せます。 日本語を少し話すことができます。 あなたは英語を話します。私は日本語を話します。 I hope you get the difference.

Yes, it is correct. About 話せます, it is the verb 話す in the potential form. So when you say: 日本語を少し話せます - You are saying something like " I'm able/ I can speak japanese a bit" You could also say: 日本語を少し話すことができる / できます But 話します is the MASU (more polite) form of the verb 話す and both are in present indicative. So they are the same, but one in plain form and the other in the polite form. So if you say: 日本語を少し話します - You are saying " I speak japanese a bit" or " I will speak japanese a bit".