The UKCA (UK Conformity Assessed) marking is the new UK product marking that will be used, subject to parliamentary approval, for certain goods being placed on the UK market if we leave the EU without a deal.
If the UK leaves the EU without a deal you will still, in the majority of cases, be able to use the CE marking to demonstrate compliance with the legal requirements and to sell products on the UK market after 29 March 2019. However, in some cases you will need to apply the new UKCA marking to products being sold in the UK.
[Gov UK – original article]
[Picture – Gov UK]