Read it aloud.

Paste a passage and your device reads it to you, highlighting each word as it goes. Slow it down, skip a sentence, tap any word to start there. Nothing is uploaded; it works offline.

Honest note: the voice is whatever your phone or computer already has, so quality varies a lot. Some voices are excellent (Apple's "Siri" and enhanced voices, Google and Microsoft "natural" voices); the default ones can sound robotic. Word highlighting depends on the voice too: where a voice does not report word timings, the sentence is highlighted instead.