The FAQ on onexox site already explains it quite well. Key info:

It has validity period of 28 months
The unlimited data only lasts for 30 days. You can buy again next month at rm35 for another 30 days of unlimited data
The unlimited data is speed capped at 3mb, but support unlimited hotspot
You also get 50 minutes talk time that is valid for 60 days. If you want more you have to buy.
As usual for onexox, there are voice and data season pass that you can buy if you need more. You don't have to buy any if the rm35 unlimited data each month already serve your needs. You can voice call using WhatsApp with data.

That's about all you need to know.