Do you want to set product gallery on one side and the rest of product page content on the other side?
That’s what the Two Column Product Page Template does. It is useful when you have multiple product images attached into each product.
To enable two column product page go to Catalog Settings > Catalog Design > Single Page Design and find Product Page Template section.
Check the Enable Two Column Product Page checkbox and save the settings.
Now product pages will have the image gallery on the right and the rest on the left.