In this situation, there are some tips to follow in order for Alexa to work properly: the most important, is to ensure that your connection is working properly.
An active Wi-Fi connection means that Alexa is able to answer your questions or process your requests.
Further best tips to follow are: place your Alexa device in an ideal location, at least eight inches away from walls or other objects that may cause interference (such as microwave ovens or baby monitors).
Be clear and make sure there is no background noise when you speak to Alexa.
Speak naturally and clearly to Alexa. Be specific, if necessary, repeat your question making it less general. Check the Alexa app to see what Alexa heard. On the Home screen, select Learn more at the bottom of the interaction card. You can read what Alexa heard, listen to your request, or provide feedback.
As an addition, you can try using Voice Training on compatible devices to help Alexa understand your speech patterns. During a Voice Training session, the Alexa app shows 25 different phrases, which you say to your device.