It's like sending, but you're sending a mental image instead of spoken words.
The limitation of not being able to read anything in the vision is to prevent "I send a vision of this entire letter I wrote to my friend with Keen Mind" abuse of the spell.
DMs should also keep in mind that only the rarest of individuals could perfectly recall everything they've seen for only 6 seconds. Definitely an appropriate time for Intelligence checks to try to pick out specific details of said vision if a PC receives one (perhaps at advantage for those with the Keen Mind feat).