Grandchild
noun
The kanji and the word are exactly the same. That means they share meanings as well.
まご
Since this word is made up of a single kanji, it probably uses the kun'yomi reading. You did not learn this reading, so here's a mnemonic to help you:
You are the grandchild of your grandfather. His favorite thing is to call you a maggot (まご). Your grandfather was in the military and is very hard on you, maggot.
新しいコンピューターを接続することは、 私の孫にとってはお茶の子さいさいだ。
Hooking up the new computer is a cinch for my grandchild.