This account has violated the Steam Terms of Service Agreement.
This account has been flagged by Steam Support for violations of the Terms of Service Agreement. Since you own items valued in currency, you are allowed to trade them for next 24 hours.
Purchasing, gifting, trading, buying and selling items on the Community Market, and cd-key activation will be disabled within 24 hours.
Account functionality will be limited. This ban is permanent, non-negotiable and cannot be removed by Steam support.
Items, skins, gifts, cards will be blocked within 24 hours after this message. You can still edit and personalize your profile. Respect steam community and other people.
More info on this topic is available here: https://store.steampowered.com/subscriber_agreement/