Google Shopping Shopify publishing fix

I have a Shopify website and have recently spotted the attached error on my dashboard that some of my products aren't publishing properly. To be honest I have no real understanding of Google Shopping and what to do so wondered if you may be able to help? I only have approx 25 active products on my shop in total..

This has never happened before and these are all existing products that have been live for a while - not brand new (they were all upldoaded over a different time period but I've noticed they've gradually all stopped publishing to Google)

I would love someone to help me fix them!