Typically, Google requires 100 post-fulfillment ("full") seller reviews with high-quality comments in the same country within 24 months, rating 3.5 stars and above to receive a seller rating and receive stars in your seller ads. You can read more about Google Seller Rating requirements here.

Typically, Google requires 50 overall product reviews. They don't typically accept reviews that mention the company name, shipping/delivery, or are "low quality"; ie "k", "luuvvv it", etc. You can read more about product review requirements here.