Well, so many information are need to learn, let's move to the basic one. I will cites the answer from the SPL FAQ.
First will always be, What is land ?

Land is digital property located within Praetoria, a secret continent now available for exploration by inhabitants of the Splinterlands.

You can access the whitepaper on https://splinterlands.gitbook.io/the-secret-of-praetoria

Next question, what the benefit of having lands on splinterlands ?

SPS Token Rewards, and the ability to harvest Resources in order to make spells and items

Okay, now we know that we can get SPS token and the resources harverst to creat spells and item. Spell and items are yet implemented on the game, it would be interesting and more complex once they are implemented and lands will have it's true utility.

Managing Our Land

Let's say we already have one, or you simply want to know how it's work on managing the lands, here is the guide that I cited from the SPL site :

1.Staking DEC/ Dark Energy
Staked DEC is required to fuel our power core. It's recommended that we begin by staking Dark Energy to the region in which we own land. After staking cards and items, we may adjust the amount of Dark Energy staked.
When staked, DEC becomes Dark Energy at a 1:1 ratio. It may be staked instantly.
Note: Stake changes will trigger a regional harvest.

2.Claim Totems
Totems must be claimed before staking to grant boosts to your productivity. Claiming totems prior to staking cards and items will provide the smoothest user experience.

3.Add a power source or Runi to individual plots.
In order to begin the process of managing our land, we must stake a Power Source to charge our workers to our plots. Both Power Cores and Runi are power sources. While Power cores require staked DEC or Dark Energy as fuel, Runi do not.
Power sources can be purchased by burning 5,000 DEC or DEC-B.

4.Stake Cards and Items on land.
After ensuring that we have a power source staked and have claimed our totems, we may Stake Cards and Items.
Be sure to note Production Boosts when determining which cards to stake to your land.

5.Build our Worksite.
After we have staked cards and items to our plots and have staked dark energy to your region, we may begin Building our Worksite. Our worksite must be complete prior to initiating resource production.
We may build your worksite instantly using Time Crystals. This allows you to avoid paying grain to complete our worksite.
We can use the Land Trade Hub to swap Grain and DEC or contribute to the Markets.

6.Use Time Crystals to Speed Up Production.
Time Crystals may be used to speed up construction by reducing the production points required for a project by 10,000. If we choose to speed up construction after building a worksite, we must pay our workers grain in order to complete the worksite.
Time Crystals may be purchased by burning 100 DEC or DEC-B for each Time Crystal.

7.Harvest
After our worksite has been built, and your plots are producing resources, we may participate in Harvests.
Grain is required to feed your workers during the harvest and upon worksite completion.
Grain may be purchased by burning 1 DEC or DEC-B per grain.

Yes, it's quite a complex system, but I'm sure this will provide a better tokenomic system for the game. The whole system is required many DEC, cards and items staked, and it may cost even more DEC for the speeding up. We would expect that DEC, cards, and item will have more utility and value on the future.

Final Words