How do I assign a velocity to an object on only 1 axis?

It gives me an error when I type in rb.velocity.x or y and try to assign it a single variable, it only allows me to make it a rb.velocity Vector2, I’ve read that it is just the way it is. But I have a problem:

private void FixedUpdate()
    {
        rb.velocity = new Vector2(direction * movementSpeed, rb.velocity.y);
        if (Input.GetButtonDown("Jump"))
        {
            rb.AddForce(new Vector2(rb.velocity.x, jumpForce), ForceMode2D.Impulse);
        }
    }

First I make a constantly updating function that sets my x axis movement velocity, then another for jumping (y axis). But since both of those arguments have to be of Vector2 type and not just x or y variables, on the Update function they override each other.

How can I stop the x velocity that shouldn’t even be there on jump function overriding the x I’m controlling and the same with the y axis?

Should’ve also mentioned I’m new to Unity and C#, probably a stupid mistake or something