Here are the steps to use select-to-speak on an Android, iPhone, PC, and Mac.

Android:
Go to Settings > Accessibility > Select to Speak. Turn on the Select to Speak shortcut. You can also point your camera at pictures or text and have them read or described aloud.

iPhone:
Go to Settings > Accessibility > Spoken Content. You can turn on ā€œSpeak Selectionā€ that will show a Speak button when you select text, as well as ā€œSpeak Screen,ā€ which reads aloud the content of the screen when you swipe down with two fingers.

PC:
At the bottom right, select the time. Or press Alt + Shift + s.

Select Settings. Accessibility.

Under ā€œText-to-Speech,ā€ turn on Select-to-speak.

Select Open select-to-speak settings. Under ā€œHighlighting,ā€ you can: Turn on Highlight each word as it is spoken.

Mac:
On your Mac, choose Apple menu > System Settings, then click Accessibility in the sidebar.
Click Spoken Content on the right.
Turn on ā€œSpeak selection.ā€