Assalamu'alaikumWhat is the ruling on using hand sign because it have different meanings like fig sign and how about other sign like when we make a gesture of gun with hand or when counting to 3 and use our thumb, index, and middle finger, because I read that this sign also use to represent trinity concept

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

The hand is one of the body parts, and thus man will be held accountable for the good or evil he commits with it. In the Glorious Quran, Allah, the Exalted, clarifies that man’s body parts, including the hands, would testify against him. He Almighty says (what means): {That Day, We will seal over their mouths, and their hands will speak to Us, and their feet will testify about what they used to earn} [Quran 36:65] and {On a Day when their tongues, their hands and their feet will bear witness against them as to what they used to do.} [Quran 24:24] This fact is also recorded in the Prophetic Hadith narrated by Imam Ahmad and Abu Dawood, “And the hands commit adultery; their adultery is the grip.” Also, when the Jews of Banu Quraydhah sought the counsel of the companion Abu Lubaabah ibn Al-Mundhir when the Messenger of Allah laid siege to them, he pointed to his throat, meaning that he (i.e. the Prophet) would slay them. However, he viewed this act as a sin, which is why he showed remorse and asked Allah for forgiveness. As such, if a person makes a sign that is viewed by people as some kind of ugliness or verbal abuse while he is fully aware of this fact, then this is considered a sin from which he should show repentance.

The same applies if he makes any sign of the Christian rituals or any other religion with his hand in a manner that indicates that he approves or supports their doctrine while fully aware of the prohibition, for this then is a sin whose doer must show repentance to Allah, the Exalted.

Allah knows best.