splashingpixels.com on "woocommerce - Problem of layout"

That is because in your theme styles you have an entry of:

.hentry { clear:both; }

So you have to decide how to work around that. You could remove it but this made break other parts of your site that depends on that. Not really sure why your theme would use clear in such a general selector. But you could try something like this to override the specificity.

.product.hentry { clear:none; }