Fundamentally Tarot is a tool of psychological, emotional, and spiritual empowerment.
Tarot is a way to get out of one's own head, whether reading for myself to get out of my own head, or reading for someone else to help them get out of their own head. Tarot is a great way to get out of your head because you can see images on the cards, using archetypes and symbols to help you see what you need to see; perhaps that things aren't as bad as you think they are, or perhaps uncovering toxic positivity.
Tarot has a structure similar to a deck of cards, and uses archetypes, so that once you begin to remember them then that knowledge is easily transferred to a different Tarot deck. I love that I can pick up a new Tarot deck with beautiful art and already have an idea of what it all means. I love the different artistic expressions of the same meanings and symbols.
Tarot is a way of organizing your thoughts and feelings, to help you see what you are having a hard time seeing, to think of things in a different way, understanding different perspectives, that sort of thing.
If you believe in God/Goddess/Source, Mother-Father-Parent God, or what not, it's a wonderful way to help you communicate with the Divine, with your angels, guides, your ancestors. It's a wonderful way to help you go within, and to help with shadow work, and mental health issues. While Tarot does NOT replace the need for mental health professionals, Tarot can help. Personally, I have used both mental health care professionals and Tarot readings in tandem and found it to be a great benefit. However, if you can't afford therapy, well, Tarot can still help you quite a bit.
Does Tarot tell your fortune? Well. Not exactly. For me, it's a wonderful way to look at what is the most probable thing that is going to come up and how one can rise to meet it (Yes, that's a Princess Mononoke reference). In this way, Tarot empowers you to change how you handle things so that whatever difficulties that are coming up can be met with more grace and ease, more zen and finesse; and sometimes, you can avoid a messy situation altogether. This is why I love forewarnings.
Tarot is also a fabulous way to help with decision making, especially when you are choosing between two good things and you can't do both; looking at the energies of each choice and the most likely outcomes. This kind of comparative reading has been so helpful for me as someone who gets anxiety-induced choice paralysis. Which brings us back full circle to being empowered, to getting out of your head, out of that spinning cycle of anxiety, into grounding and calming the mind to invite in clarity.
I hope this helps, and feel free to ask questions in the comments!
Note: Image above is the Czech version of the Shadowscapes Tarot (my fav), featuring Queen of Wands, Temperance, and the Hierophant; respectively.