This idiom or expression like phrase means:

Steady.
In a balanced way.
A condition of equal opportunity.
No particular advantage in any direction.

Also:
On even keel.
On an even keel.

This idiom or expression refers to:

Equal treatment.
Equal opportunity.

When someone says “I welcome a three way meeting if we’re on equal footing,” they mean something like “I’ll meet with them if we’re all treated equally and with mutual respect.”