Google Photos in 2020 tries to hide photo captions.
Here's how you find them.

by Jon Claerbout
The big advantage of Google Photos over my photos is that Google Photos incorporate captions.   Many of my photos at Google do have captions.   Bizarrely however, Google does a sly job of hiding them.   This is inane, I know.   When a photo of mine has a caption you should be able to see it.  

How you can be sure you see captions depends on how you enter, both your hardware entry (computer, tablet, or phone; Apple or Android) and the choice you'll make among the next two:

The best way:
Select (click on) the first picture.   If an "Info" side window of information appears, the caption is there but it wastes too much space.   Find the X in its upper left corner and blow away the info.   Move your mouse pointer to near the lower left corner atop the left edge of the caption.   If a caption appears, move your pointer to its first word.   You should advance frames with arrow keys.   If you use your pointer on the arrows on the screen, and leave your pointer there you will lose the captions!   When you choose "Fullscreen" among your window options you also need to reposition your pointer atop the captions.   When a photo changes size or aspect ratio, you might need to move your pointer.   Bizzare, eh?

Not the best way:
The icon of three vertically stacked dots is a menu. It's top item is Slideshow. Select it and slides will change automatically but I don't find any captions.

Even my best way is not guaranteed to work. You might need to keep your pointer moving near the caption location, or maybe you need the screen wider.