It's supposed to go to provinces and territories for their vaccine rollout. There is no specific list of what it needs to be used for.
The budget document—I have it here—talks about the things it could be used for. The types of examples are on page 63 of the budget and talk about recruiting and training “immunizers”; “establish mass vaccination clinics”; “set up...vaccination units”; “engage Indigenous communities to advance vaccine rollout”; and, of course, “reach vulnerable populations through community-based vaccine efforts”.
The bottom line is that provinces and territories can use the money based on their unique circumstances.