The word chamas (חָמָס Strong’s Hebrew 2555) means violence or wrong, as in an injury or injustice, that is committed against another. Looking at the occurrences of the word chamas in Habakkuk, it is often the case that either connotation could work and both may be implied.
Habakkuk 1:3-4 NKJV
For plundering and violence are before me; There is strife, and
contention arises. 4 Therefore the law is powerless, And justice never
goes forth. For the wicked surround the righteous; Therefore perverse
judgment proceeds.
The context of Hab 2:17 regards a question that Habakkuk inquires of God:
Habakkuk 1:13
You are of purer eyes than to behold evil, And cannot look on
wickedness. Why do You look on those who deal treacherously, And hold
Your tongue when the wicked devours A person more righteous than he?
Habakkuk 2 lays out God’s answer. The passage speaks of how the things that men amass by unjust means will return to haunt them. It is a reminder that the earth and all its riches, whether we speak of trees or people or glory, belong to God, and those who claim possession or abuse it will face retribution.
Habakkuk 2
6 Woe to him who increases what is not his…
8 Because you have plundered many nations, All the
remnant of the people shall plunder you
9 Woe to him who covets evil gain for his house…
11 For the stone will cry out from the wall, And the
beam from the timbers will answer it.
12 Woe to him who
builds a town with bloodshed, Who establishes a city by iniquity! …
13 Behold, is it not of the Lord of hosts That the
peoples labor to feed the fire, And nations weary themselves in vain?
Hab 2:17 sums up God’s answer. But what is the meaning of “violence done to Lebanon”? Known for its natural resources, Lebanon is a wooded mountain range on the northern border of Israel. According to BDAG, the words “violence done to Lebanon” likely refer to the cutting down of its trees ([biblehub.com]https://biblehub.com/hebrew/3844.htm)).
Isaiah 60:13
“The glory of Lebanon shall come to you, The cypress, the pine, and
the box tree together
The tree has rich metaphorical significance in both the OT and NT. Given that God’s answer begins with “behold the proud, his soul is not upright” (Hab 2:4), the “violence done to Lebanon” can be understood as a metaphor for how God will bring down the proud.
Isaiah 10:33-34
33 Behold, the Lord, The Lord of hosts, Will lop off the bough with
terror; Those of high stature will be hewn down, And the haughty
will be humbled. 34 He will cut down the thickets of the forest with
iron, And Lebanon will fall by the Mighty One.
Of its many figurative uses, there is one other that needs mentioning: the tree as a symbol of the righteous man (cf Ps 1:3, 92:12, Ez 17:22-23) - or, as some understand it, as a symbol for Christ. Therefore the “violence done to Lebanon'' can also be interpreted as a reference to the cross.
Such an interpretation drastically alters the message of Hab 2:17. What appears to be a threat of retribution instead becomes a promise of forgiveness (cf Gal 3:13, 1 Pet 2:24). Behind the “violence” we therefore find the hidden depths of God’s mercy.
Habakkuk 2:17
For the violence done to Lebanon will cover you
God’s answer to violence then is mercy. The OP asks, “What is the significance of this word, especially for us today?” As we face the increasingly grave consequences of human cruelty and injustice, the message of Hab 2:17 remains as urgent as ever. In my opinion, the violence in our world will continue unchecked unless we follow God’s model of retribution, which means to respond to wrong/violence with mercy. The call to emulate God’s goodness is key to the life of a Christian, for whom the message of Hab 2:17 may still hold a warning: unless we who are grafted into Christ bear fruit, we too may suffer the “violence done to Lebanon” (cf Jn 15:5-6, Mt 3:8-10).