Design thinking is a methodology for designing things, often products. It has 5 steps:
1. Empathize. Find your intended user and try to understand them, their expectations, wants, needs, and fears.
2. Define. Based on understanding your user, what are you trying to actually do? What are the problem(s) you want to solve for the user?
3. Ideate. Get a bunch of people in a room and have a no-judgement brainstorming fest around solving the problem(s) you defined. Come up with a ton of ideas! Then look at them all critically and remove the less priomising ones.
4. Prototype. Make MVPs for a promising idea or ideas.
5. Test. Take your MVP to your target user. See how they react. Go back to prototype and adjust the idea based on feedback, or pick a different idea out of the ideation process if this one is a bust. Repeat until your prototype is good enough that you're confident to scale up.
Within each of these steps, there are a few tools/techniques you can learn to structure them more if you like. There are also no shortage of experts and consultants who will take your money to expound on the finer points of each part of the process. You can go as deep into the rabbit hole as is useful.