During a Microsoft Teams meeting you can, if allowed by the tutor, share your screen so everyone can see what you wish to demonstrate or explain. The white rectangle buttons, next Leave opens the Share Tray. From you can choose to share your entire screen or a Window, one of the open applications you have open on your computer.
It is also possible to share using PowerPoint live. This loads your presentation into the meeting and gives features such as stand out mode, placing you in front of the slides, and private viewing.