Spawn tiles, are usually used to mark a tile as a spawn tile, but this can be done with a simple property associated with the tile or map location.
Each SDK has some way to implement collision, so it either supports an extra layer, or property to determine collision. Check the SDK documentation to see what it supports.
If there is no support for collision, you can roll your own, using any of the ideas mentioned above (collision layer or a tile property).
In Tiled documentation, there is a link to some tutorial videos.
One of the videos has a simple example of what a collision layer is.
Basically, for a simple implementation, whenever there is something on that layer, you can't go there.
If you need several types of terrain or collision types, like hearth, water, swamp, wall, door etc, you can check what is set on each location on that specific layer, and act accordingly.