First, I'll address a small error in your question: The words "the" and "is" are not necessary, so you should say, "Does talking to yourself improve your speaking skills." My answer: Yes, I think so. By talking to yourself, you can begin to develop muscle memory in your mouth for the new and possibly very different sounds that you will be making in your target language. It can also help you remember vocabulary you have recently learned. Of course, talking with a native speaker is the best practice, but talking to yourself will always help you more than not talking at all.

Hi Sergie, I agree with Lee that it can help, at least with practicing the sounds and connecting words. It also helps you start to think in that language, and process ideas too. However, speaking is about listening and reacting to other people too, and speaking to yourself won't really help with that. So, practice speaking to others too. Good luck!