Sure, we can ask Siri or Alexa to answer a question or perform an action for us. But Siri and Alexa can only respond to pre-programmed questions and commands. (You can find a detailed explanation of how personal assistants work here). They do not really understand what you are saying, and you cannot have a real conversation with a personal assistant like you can with another person.
Three-year-old children understand language. We have computers that can beat chess champions. Why is building computer systems that understand natural language so difficult? (Natural languages are the languages that people speak as opposed to computer languages).