David Raymond is right, we need a lot more info to offer anything resembling "wise" advice.
If I have to guess, your most immediate solution to just make it work, regardless of how well it functions (and assuming the "missing" s table in your query is actually called "s"), would be to do:
```
UPDATE t1 SET t1.start_station_name = (
SELECT s.start_station_name
FROM s
WHERE s.start_lat = t1.start_lat AND s.start_lng = t1.start_lng
)
;
```
Note that this will replace ALL station names in t1 with whatever they are in "s" for the same lat-long. Please back up your files before doing this, and give us much more information for more useful suggestions.
Note Also - if lat and lng are REAL (Floating point) fields, [the equality check x.lat = y.lat is not guaranteed to work](https://bitbashing.io/comparing-floats.html) due to small possible differences in float values that seem equal to the naked eye.