v1-2: The prophet's question, "What do you see?" used of Jeremiah (Jer 1.13); Amos (Amos 7.8; 8.2); the Lord Jesus did everything He saw the Father do. This is another vision, not a dream, as Zechariah had been awakened from his sleep.
v3: The two olive trees, the two anointed ones (v14); the two witnesses of Rev 11.3-6.
v4-5: Zechariah asks questions to learn and understand, see v11-12; 2.2. 1 Pet 1.10-11; where we lack understanding we should ask. The clear answer is not immediate.
v6-7: The lesson linked with the vision, given before the answer. Obedience and faith take precedence over understanding.
"By my Spirit," is God's way of working, not by human might or power. Here is the real power of God's grace in our lives. He takes a Zerubbabel, and moves a mountain!
v8-10: The immediate challenge was to complete the construction of the temple. Along with Haggai, this was part of Zechariah's ministry, to encourage the people to finish the task.
Special blessing upon Zerubbabel; he laid the foundation of the temple, and he will be blessed by seeing it completed. Some rejoice to see the plumb line in his hand, but others despise the day of small things; the work is proceeding slowly, but it is proceeding; it is enough that God is blessing; and therefore we should rejoice.
The seven lamps (v2) are the eyes of the Lord, seeing all things on the earth.
v11-14: The two anointed ones depend on the Lord; their oil is from the lampstand, see Rev 11.