What engine and gear oil are best for this car?

The owner's manual should be available online from Nissan, you would need to use the Nissan site in your particular country though as they are somewhat locked so that people in the US cannot access manuals for cars that were not sold here under that name, for us the Tiida came in as a Versa, but with different engines and options. However, they used the same engine and transmission in a few models. The engine should use either 0W-20 or 5W-20 engine oil, depending on what is available. 4.0 L with a filter change. For the transmission it takes Nissan CVT Fluid NS-3. This one is somewhat a critical thing as CVT transmissions are very fussy about the fluids used. Checking it isn't difficult, but it does require the specific tool set KV311039S0. You need the car on a level surface engine running at an idle and then remove the charge plug. Then you install the special tool and add approximately half a liter through it. Then remove the tool and see if fluid drains out. If it does let it run until it only has a slow drip, remove the tool (A in image) and reinstall the plug. For a full fluid exchange it is best to use a fluid extraction system to flush the fluid, lacking that you can remove the drain and overflow tube and drain the fluid, however for this method you really need a lift to do the job as you need to add fluid, lower the car, shift into each gear with the engine running and your foot on the brake, then use a scan tool to watch the fluid temperature, then you lift it again, remove the drain and overflow tube (shown in the second image) and let the fluid drain out, then fill the transmission with about 3 liters of fluid, install the drain plug, lower the car, run the engine and cycle through each gear again. Raise the car back up, remove the drain plug again to drain out that fluid, then remove the transmission pan and clean it all out. Then reinstall the pan and the overflow tube and fill the transmission using the fill adapter. It holds almost 7 liters if you manage to remove it all, but you simply add fluid, run it through the gears again with the engine running, then add fluid and remove the fill tube until fluid runs out like you were checking it.

Nissan usually has the owner's manuals under the support sections on the various sites.
Which country was your car sold in?

A CVT is a different form of automatic transmission. It doesn't actually have preset gears but instead uses an internal belt to "shift". Nissan used that style of transmission in 2012 in most of their cars, unless you have a manual where you need to shift each gear yourself. The CVTs are very touchy when it comes to the fluids used and using the wrong one will cause multiple problems up to complete failure.
They are one of the few items I suggest owners use a dealer for service, that way if something goes wrong it is still covered under warranty.

None of the manuals on the US site will work with your car, they are built in a different factory with many different parts tailored to the countries they are sold in, the engine and transmission would be the same as those were shared but things like tires, suspension parts, exterior parts and even engine programming will be different because they are not required to meet US laws.

Try this site instead:
https://www.nissan-me.com/

Or here:
https://www.nissan-me.com/owners/driver-guide.html

You are welcome. That is one of the issues with many auto makers. They keep a similar car or name on a vehicle, but they are really not the same one underneath. There are a lot of examples throughout the entire spectrum of vehicles of this. It makes things interesting.