DC is just 5 and an able child. They surprise me everyday with how quickly they learn.
I take it they're your first/only?
The thing is most parents feel that way.
Ime often the difference between the child who is (eg) able to play monopoly and the child who can't at 5yo is opportunity.
The reason why I say I take it they're your first, is that things that we were "Oh wow! Look what dd1 is doing", dd2, who is 3 years younger, did 2-3 years earlier because she was determined not to miss out. Ds sometimes (if it interested him) at 3 years younger still, did things 5+years earlier, than what impressed us with dd1!
It wasn't that dd2/ds were better/more able, simply that they had the opportunity at a point dd1 didn't, and the pull of wanting to do what their sibling was doing.
Also if they start doing something and you act all amazed and as though it's the most brilliant thing in the world, then they want to do it more and will be more likely to succeed. It's a great way of getting them to learn things without they realising. 
It depends on how you frame it:
"Had a lovely game of Monopoly, was delighted how quickly dc picked it up. Lovely now they're getting old enough to enjoy games we can all enjoy (did not enjoy the years of Pepper Pig pairs!)"
is nice and sweet, and I'd think was quite a nice thing to say.
"Dc is so clever and amazes us all constantly with their ability to pick up things far beyond their age. Today they played Monopoly with us. Monopoly! For a 5yo! They knew every rule and were even correcting us within a couple of rounds of the board. They even managed to read the words "premium bonds" and "dividends" on the community chest with no help from us. I am astounded. They are going to set the world on fire with their intelligence!"
Is one of those statuses that rubs people up the wrong way, it's just wanting to boast and nothing else. It makes me want to reply what age mine played monopoly. (although I wouldn't. I'd probably ignore the post, and then block them if they did that too often-as I did with a certain relative who posting something very similar to the above)
Save the second one for boasting to the grandparents. Although be aware that they may then repeat it and let the other relatives roll their eyes in private (and suggest a game of monopoly with their carefully trained 3yo in tow...
)