“Get up, get up, Deborah!” Although most other English versions say “Awake,” Deborah was not asleep, nor even mentally “asleep.” She was waiting for guidance from Yahweh and, especially given the tense time, would have been wide awake both physically and mentally. When she got the revelation from Yahweh to move forward, then she needed to move quickly and decisively, thus the imperative fourfold exhortation to “get up.” Using a different Hebrew word, Barak was told to “stand up” and get moving.
“speak forth a song.” This is recounting the events before the battle, so Deborah is not rousing herself to action just to sing a cheerful melody. In this case, her “song” was most likely either her prophetic call to Barak to gather an army against the enemy (Judg. 4:6-7) or her final call to start the battle (Judg. 4:14), or perhaps even both.
“capture your captives.” This was a refrain commonly spoken by women as their men returned home from a battle with loot and possible captives (cp. Ps. 68:18).