You create a shimmering sword-shaped force field within casting distance and cause it to remain present for the duration of the spell.
Mordenkainen’s Sword 5e
Level: 7th
Classes: Bard, Wizard
Casting Time: 1 Action
Range: 60 feet
Components: V, S, M
Duration: Concentration, up to 1 minute
When the secret sword appears, you may make a melee spell attack against a target of your choice within 5 feet of the sword. On a hit, the target takes 3d10 points of force-field damage.
For the duration of the spell, you may move the sword up to 20 feet on your turn with an attached action. The destination of the move must be visible to you, and after the move is complete you may also make that attack again against the same target or a different target.