This chapter of the guide to Dragon Ball Z: Kakarot has a walkthrough for Close Encounters of the Troublesome Kind side quest.
Time frame: From Android Terror Arrives - Episode 5: Meeting the Mysterious Monster to Episode 5: The Mad Scientist's Lair
Reward: 79,713 EXP, D Medal, Porunga Plush, Fancy Ring
Where to start: Western Area, as Piccolo.
Speak with the tourists and then go to Gizard Wasteland. You need to kill a dinosaur.
You can fight it by staying in the air. This way, you will avoid damage.
Get the dinosaur's meat and then go back to the quest givers. Receive your reward.