There are two places in Workspace where you can choose to return work to learners. In both of these places, you can return either for further edits, or as the final assessment, and you can choose to include a grade or not.
The first method is on the evidence card itself. In the Activity Status area on the card, select 'Submitted', and in the pop-up that shows listing all evidence submitted by learners add a grade/assessment in the box (or leave it blank) and then choose whether you want to return this for further editing by the learner, or return it final (in this case the learner will not be able to submit this evidence again):
The other way to return evidence is to go to the Activity Summary page, where you can quickly open and return all work. The procedures and buttons for returning and grading work are the same
This is how it will show to a learner on their card in the Workspace: