return productDao.selectList(new QueryWrapper<Product>().eq("is_delete", 0));

This code is using MyBatis-Plus library to retrieve a list of products from the database.

The method `selectList()` is called on an instance of `productDao`, which is a DAO (Data Access Object) for the `Product` model. The `QueryWrapper` is a utility class provided by MyBatis-Plus to construct SQL queries using a fluent API.

In this case, the query is looking for all records in the `Product` table where the `is_delete` column is equal to 0 (meaning the product has not been deleted). This is achieved by calling the `eq()` method on the `QueryWrapper` instance and passing the column name and the value to compare against.

The method will return a list of `Product` objects that meet the criteria specified in the query.