How Much Thrust?

SLS rocket. Image credit: NASA

8.8 million pounds, 4.0 million kilos or 17.3 million newtons (the SI unit of force). That's 15% more thrust than the Saturn V rocket, used for the Apollo missions to the Moon in the late '60s and early '70s.
The SLS or Space Launch System is the rocket that's being used for the Artemis missions that will once again carry astronauts to the Moon. (Artemis was Apollo's twin brother in Greek mythology).
Huge amounts of thrust are needed to accelerate spacecraft, so that they can escape Earth's gravity. The escape velocity of planet Earth is 11.2 km/s or 25,000 mph. We can't simply use rockets to travel point-to-point to the Moon as it would be inefficient and require continuous rocket firing and fuel use. By travelling fast enough initially, hence the massive engines and fuel tanks, we can "coast" there, like a car with one's foot on the clutch. The principle is based on Newton's first law of motion—so once an object starts moving, it keeps moving uniformly, unless another force acts on it, Earth's gravity in this case. (That's why the Voyager spacecraft are still moving out beyond the Solar System). Technically, a spacecraft is falling back to Earth under the influence of the latter's gravity, but in the case of lunar missions, the Moon and its gravity "take over" when the craft is close enough, allowing it to be injected into lunar orbit.