Cannot understand Time Dilation

Hello friends, I have seen lots of videos and articles but cannot seem to grasp what time dilation is.

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1. Saw this post https://www.reddit.com/r/space/comments/wdacvw/time\_dilation\_is\_very\_confusing\_to\_me/. I know that planet was close to a black hole and had strong gravitational pull. **Lets assume people on foreign planet are currently on earth, sitting with me, we both have an analog and a digital clock with datetime 1st Jan 2000 00:00:00**. They have a 1 hour TV show on their mobile. **They go to foreign planet within 1 second of earth time (just assuming), watch the TV show and come back within 1 second of earth time, when we both match our clocks, their clock will show 1st Jan 2000 01:00:00**? and our clock will have **1st Jan 2007 00:00:00**? How come the clocks started to tick slowly? **How come video their mobile played in so slow that it took 7 years of earth time?**
2. If I am able to see him from earth through telescope, he will appear to move in ultra slow-mo? Is that something to with the light that comes from that planet and reaches to my telescope/eyes?
3. Saw the clock example at start of video https://www.youtube.com/watch?v=yuD34tEpRFw&ab\_channel=ScienceABC**. I get when Einstein is moving away from clock at nearly speed of light, the light of the next tick of clock, cannot reach him so clock appears to have stopped but for people near clock would see clock ticking at normal speed. This makes sense. But what if Einstein was also holding a clock when on train, what if he comes back to clock tower, then the time at clock tower and his clock will match?**

by iamumairayub