A relation is in second normal form if it is in 1NF and every non key attribute is fully functionally dependent on the primary key.
It is in first normal form
All non-key attributes are fully functional dependent on the primary key
The First Normal form deals with the atomicity whereas the Second Normal Form deals with the relationship between the composite key columns and non-key columns.
To achieve the next progressive level your table should satisfy the requirement of First Normal Form then move towards the Second Normal Form.
Let see the example from above 1st Normal From
Table is not in Second Normal Form because the price and tax depends on the item, but not color.