Lanes:
DotA is composed of 3 lanes which people will utilize to gain both experience and gold.
We have the short lanes, the mid lane and the long lanes.
The short lane(Safe lane) are for the dire the top lane and for radiant the bottom lane.
Short lanes are known for having the creeps meet close to your own tower and having access to easy creep-pulling, keeping the lane forever in your favor, theoretically.
They also have your own jungle next to you, allowing junglers(if you have one) to support said lane with ganks.
The mid is the same for both teams.
The mid is known for being a lane where rune-control and experience matters more than any other lane, small advantages in this lane can snowball into kills on your opponent, this is why creep-blocking is important(Can get you to level 3 before your opponent does, theoretically).
The long lane(Hard lane) is the top for the radiant and for the dire the bottom lane.
They are known for having the creeps meet far away from your tower, creating a risky lane for yourself where you are vulnerable. They also have the enemy jungle near them, further increasing the risks of this lane.
Last hitting and denying:
Getting gold and experience is essential for a team and the easiest way to achieve this is from getting last hits.
Last hitting a creep is probably the most important skill in DotA, it comes from taking your time and then attacking a creep when you know that your attack will be the killing blow, in most lanes you have a 'farming' hero that will have the priority and be allowed to take the last hits, as it is ineffecient to have two players fight for last hits.
But of course it's not this simple, you will not only fight your own judgement regarding when to attack, in DotA we also have the concept of denying, which is very simply put killing off your own units so your enemy does not recieve any gold and reduced experience.
Melee heroes are not punished as heavily as ranged heroes when it comes to the reduced experience from denied units, to make up for the fact that they are melee.
Denying isn't important just for preventing the enemy from getting experience, being able to attack your own units when they are sub 50% HP allows you to hold the creep waves at an equilibrium near your own tower, thus giving you safe farm.
Creep pulling and stacking:
Creep pulling is the act of making your allies creeps fight the creeps in the jungle by aggroing jungle creeps and having them aggro your lane creeps. Thus denying your opponent of gold and experience whilst allowing a support to last hit jungle creeps for extra farm that would normally not be available to the support.
This is mostly done at the medium size camps near the short-lanes, but just pulling is not very effecient because a creep wave is stronger than a medium sized creep camp and they will eventually just return to the lane and push it in the favor of your opponent.
So how do we solve this?
With stacking, units in the jungle in DotA will respawn at their camps at X:00 outside of the first spawn timer which is 0:30.
They will only respawn if there are no other units near the camp, and thus, aggroing the creeps in the camp and pulling them away from their camps at the right timing will stack the camp, allowing for 2 set of medium-sized creeps in the jungle, this stack will be enough to kill an entire creep-wave.
Stacking can also be utilized by supports to stack big camps and ancient camps for a carry to farm later for increased gold-income.
For an easier and more visual explanation:
