Presumably, they are looking at the verb form, the present progressive, so the underlying concept of that sentence is that the action is occurring now. The rest of my answer assumes that this is the point they are looking at. The gender is not terribly important, though I'd have had Sophie down as female, so there might be something worth clarifying, but as they're using a name and not pronouns I think it is the verb that is the main aim. There's nothing in the sentence to tell us about the person Sophie is speaking to so it's outside the scope and focus.
As people only speak in languages, the second question is artificial; if not a language, then what could she be speaking? Simply asking whether she's speaking Spanish/Japanese, etc, would get a more natural response.
The main point of the present progressive/continuous, in this sentence, is that the person is performing the action at the time of speaking, which may be expressed in very different ways in other languages. Try to imagine that you are looking at a script of a language that is very different from your own and does things very differently; does answering those questions help you get the point that be + -ing is used for things that are happening at the time of speaking? Some of your students might be struggling with letters that are just scratchy symbols, might have a very different system of pronouns, might have no tenses and aspects, or very different ones. We say she's speaking English when it's true at the time of speaking and unfinished, which is different from she speaks English. But then imagine hearing someone on the phone speaking beautiful English- you'd probably say she speaks good English not she is speaking good English. Things that may seem simple to us are often very complex and baffling to speakers of other languages at first. If you can remove some of the barriers, you'll make their learning lives a lot easier.
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