Once started, your body will usually stay in ketosis even with a modest and non-trivial budget of carbs, on the order of maybe 10-20g, excluding fiber.

That allows for a wide variety of veggie choices, as well as a some wiggle room for modest servings of nuts, legumes, beans, etc

But basically there's no room at all for stuff like breads or rice or potatoes or sweetened drinks except as the finest accents. Never as the centerpiece of a meal.

It's a very different way of living and eating, but can feel extremely invigorating and seems to be broadly healthy for most people.

Some vegetables are OK on keto IIRC. Leafy greens, asparagus, squash. Avoid the starchy ones.