Heya all,
Is there a way so I can count the number of images inside an Album and show that under or behind the Album title under the thumbnail?
You can display this in a couple different ways.
In BL2 and BL3 you can use phplugins. There is code for it in the phplugins-pangolin-sample.php file found in the backlight/custom/phplugins/ folder. The function starts on line 492.
The function can display the information in the page body. The sample function in the phplugins file will display Album Title, Album Description, and Number of Photos.
The other way is to use metadata tokens for the image thumbnails. That can be made to display, for example, 3 of 125 images.