Hello Dipobhasadhamma,
There are two main usages in Buddha Dhamma. In both, “paramattha” (“parama” + “attha”) means “ultimate truth” and “sammuti” means “conventional or adopted by humans”.
1. The sammuti version of our world is to say it has humans, animals, Devas, houses, mountains, planets, stars, etc.
– But in Abhidhamma all that can be reduced to 28 types of rupa, 81 types of citta, and 52 types of cetasika. That is the paramattha version.
– Living beings with the perception of sammuti version of the world engage in unfruitful activities seeking pleasures in this world and only end up with NET suffering.
– When that understanding comes, one becomes an Arahant and attains Nibbana (separate from this world). Nibbana is the true paramattha sacca in Buddha Dhamma.
2. There are other versions of the usage in different forms.
For example, when we use such expressions as ‘I’, ‘you’, ‘man’, ‘woman’, ‘person’, ‘individual’, we are speaking about things that do not exist in reality. They exist only for short durations within the beginningless rebirth process.
– the Ultimate Truth is that there is no ‘person’, ‘individual’ or ‘I’ that will last. The only unchanging reality is Nibbana.
However, while living in this world, an Arahant or even the Buddha needs to use conventional terms like “I” and “me.”