It just means if the Elizabeth line station ("custom house for excel") near the hotel is closed on the weekend, and you need to get to London city centre (or Heathrow airport) you're looking at a MUCH longer journey with lots of stairs, lots of walking to transfer between lines, possibly broken elevators, possibly broken escalators, and so on. You will eventually get to where you need, but you will arrive much later and much more exhausted.

Also, if they decide to suspend the part of the DLR section near the moxy excel hotel, you're looking at only bus journeys only, or taxi or uber ride.

Getting round in London on weekends is always a lottery.
Sometimes it's fine....other times it's a logistical nightmare.