GUESSING (ADIVINAR) IS A KEY SKILL THAT YOU NEED TO DEVELOP WHEN YOU ARE SPEAKING A FOREIGN LANGUAGE
It is very unlikely that you will always fully understand everything that you hear in English. So, it is important to learn how to be comfortable with these unknowns. You need to make sure that you develop a technique that allows you to guess from the context as much as possible.
I don't understand everything that I hear in Spanish. Many things I don't understand at all!! When I don't understand something I immediately try to look for clues (pistas) as to what the person might be trying to express. It will not always work but it can help from time to time (de vez en cuando).
Hope that helps!
Soy el director de Daniel Smith + Partners. Tengo más de 10 años de experiencia enseñando inglés a españoles.