iOS comes with a Speak Selection accessibility feature that will read selected text to you. To enable this feature, on Settings app, go to General > Accessibility > Speak Selection.
Tap the “Speak Selection” switch to turn it on. You will have the option to select the language and voice under “Voice”, adjust the speaking rate and also highlight words as they are spoken.
Speak Selection will work in apps where you can select or highlight text such as Mail, Notes, Messages, Reminders and Safari. Once this feature is enabled, popup bubble menu for text selection will have a new “Speak” option. Tap to hear your iPhone speak your text selection to you.
Speak Selection also has a nice trick that it can decode and explain Emoji for you. If you’re reading this on your iPhone, highlight this Emoji 💩 and let Speak Selection explain it to you.