Is this a tub, a box, a bottle? Or is there a better word for it?
Unfortunately, the product page at tesco.com doesn't say what the tablets come in - only that frying information isn't applicable... ;-)
Seeing as it's medicinal in nature, I'd say it was a bottle, or more specifically, a pill bottle.
If it were a liquid medicine on the other hand, I'd refer to it as a vial.
If I were to be more generic, I'd simply refer to it as a container.
Edit: This is a container for another, similar Tesco supplement (in this case it's a multivitamin container)
The manufacturer refers to the container as a bottle.
To me (Russian) it's definitely a 'can', not a 'bottle' or a 'tub'.
But if we speak about medicine it could really be a pill bottle, pharmacy bottle, or a pill container.
It could also be a jar, maybe. Plastic jar. I don't agree with vial, even a plastic one, since I haven't found any images of a vial looking something similar to the given image.