Territory is whole world for a Lion.
Territory is displayed in your den, next to your Lion's name.
You start with territory of size 2. A little plus next to it shows that you can expand it.
Territory - holding lionesses and cubs
You yourself aren't counted towards territory space.
Territory shows how many subjects you can have - territory of 7 means you can have 7 lionesses.
You need one extra territory space for a breeding, to ensure your ladies that you can support future cubs.
So with 7 territory and 6 lionesses, you can breed and get them pregnant. Cubs won't take territory space until they grow up - but make sure that you have enough of space for them if you want to keep them and they're already teenagers! (over 1 year old)
You can always free territory space by chasing off lions.
Chasing off lioness frees 1 post.
Chasing off lioness with little cubs under 1 age will also make the cubs run away, frees 1 spot.
Chasing off a cub under 1 year old will make lioness leave too, freeing 1 spot.
Chasing off a cub between 1-2 years won't cause any repercussions.
Territory size and expansion
You can buy more territory up to 10 size by clicking a plus in your den and spending Silver Beetles on it.
Above 10, up to 20, your only way to get more territory is to attack another lion. Attacking other lions
You can attack for territory as many times a day you like - but another lion can be attacked for it only ONCE a day.
You can't attack a lion who has only 2 territory.
From territory size 20 to 30 only way to get it expanded is to spend 2 GB per space. It's a luxury.
Territory maximum size for now is 30 for a single lion to take care of.