Whey protein concentrate typically contains some lactose, as it is made by filtering whey, which is a byproduct of cheese production. The exact amount of lactose in whey protein concentrate can vary depending on the specifics of the manufacturing process, but it is generally higher in lactose compared to other forms of whey protein, such as whey protein isolate. Some whey protein concentrate products may contain lower levels of lactose, or may be specifically formulated to be lactose-free, but this can vary between products and brands.
If you are lactose intolerant, it may be advisable to use a non-dairy protein source.