This is first of all a shampoo, but the formula does include conditioning actives. According to the product information, beluga caviar extract helps soften the hair surface, and panthenol holds moisture in the hair fibre. That means hair can feel smoother and less coarse after washing alone, particularly on short or medium-length men's hair that is not very dry.
Whether you still need a separate conditioner depends on your hair's condition. If your hair is fine, short and your scalp is oily, this shampoo may be enough. If your hair is long, chemically treated, bleached, very dry or prone to tangling, a rinse-out conditioner applied to the lengths and ends will add slip, make detangling easier and leave a heavier layer of moisture that a shampoo is not designed to deposit. If you use heavy wax or gel regularly, keep conditioner off the roots so the scalp does not feel greasy.
A practical approach: try this shampoo on its own and assess the result. If the lengths feel comfortable, smooth and easy to comb, there is no rule that says you must add conditioner. If they feel dry or stiff after drying, follow with your usual conditioner or a small amount of hair oil on the mid-lengths and ends. Adjust based on your own results.