The caption gave a bit of background about the pic, which shows the duke and duchess (before they were even bestowed those titles, back when they first started dating) securing a tracking collar around an elephant. (Royals! Their dates are nothing like ours...)
"Prince Harry’s long time commitment to this cause as well as a glimpse into the work he and The Duchess of Sussex did in 2017," the caption states. "Their Royal Highnesses travelled to Botswana to assist Dr. Mike Chase of Elephants Without Borders in equipping a bull elephant with a satellite collar."
The caption continues with an explanation for the collar: Approximately 100 elephants are poached or killed every day for their ivory tusks. The satellite collar allows conservationists to track their migratory patterns and protect them from human wildlife conflict.
According to the post, the elephant pictured was sedated for ten minutes before he was up and back with his herd (the next slide in the Instagram shows a video of the elephant getting back on his feet).