The word translated in the English as "sign" in John 2:11, 4:54, 6:14, & 12:18, is the Gr. "σημεῖον", or "sémeion", and means a sign, miracle, indication, mark, or token. (1)
The choice of translating it in one place as a sign and in another place as a miracle alternates between translations. The KJV uses "miracles" in John 2:11, whereas the ASV, RSV, YLT and others uses "signs. The CEV and NET have it as "miraculous signs".
The miracles were the signs that Jesus (Yeshua) had been given glory and power from the Father (YHVH) for the people to know who He was and who had sent Him.
"22 Ye men of Israel, hear these words; Jesus of Nazareth, a man approved of God among you by miracles and wonders and signs, which God did by him in the midst of you, as ye yourselves also know:
23 Him, being delivered by the determinate counsel and foreknowledge of God, ye have taken, and by wicked hands have crucified and slain:" (Acts 2:22-23, KJV)
Miracles were always used for the sign, the mark, the indication of approval and authority from YHVH. They indicated His authority was extended to the one He had sent to the people, and were given to His prophets, and to the Messiah so the people would know to listen to them.
The miracles and signs were always for the purpose of confirming His word. Therefore, the English words "signs" and "miracles" serve the same purpose and are used interchangeably to indicate God's authorized messenger.
Notes:
1) Strong's Greek 4592, sémeion - Biblehub