Gravitational potential energy near a surface is $U = mgh$ — U equals m g h, with $m$ the mass in kilograms, $g$ the local field strength, and $h$ the height above a zero you chose yourself (the bench, the floor, the ground). That chosen zero is fine while g barely changes. Leave the surface and it fails, so astronomy uses the honest form: $U = -\dfrac{GMm}{r}$, with $M$ the central mass, $m$ the orbiting mass, $r$ their separation in metres, and the zero fixed at infinite separation.

Hence the minus sign, which alarms everyone once and then never again: zero is infinitely far away, so everything gravity still holds sits BELOW zero. Negative means bound. Climb outward and $U$ rises toward zero; reach zero with nothing to spare and you have just barely escaped. Note also the single $r$ downstairs — the force has $r^2$, the energy has $r$, and mixing them is the classic slip.

Put that at exactly zero total energy and you get $v = \sqrt{\dfrac{2GM}{r}}$, the escape speed: the launch speed from distance $r$ that arrives at infinity with nothing left. Set it beside the orbital speed $\sqrt{GM/r}$ and only a factor of $\sqrt{2} \approx 1.41$ separates them. Orbiting is falling forever; escaping costs 41% more speed and buys the entire universe. And notice the escaping object's own mass is nowhere in it — a pebble and a spacecraft need exactly the same number.