Meaning of the poem 'Before Action'

Hi, I'm Jessica, I'm just immigrant from another country.

I'm very interted in the poems

but My English isn't good enough to understand actual meaning of the poems.

So I wonder if someone can help me

So this is the poem.

Before Action

We always had to do our work at night.

I wondered why we had to be so sly.

I wondered why we couldn’t have our fight

Under the open sky.

I wondered why I always felt so cold.

I wondered why the orders seemed so slow,

So slow to come, so whisperingly told,

So whisperingly low.

I wondered if my packing-straps were tight,

And wondered why I wondered. Sound went wild . . .

An order came . . . I ran into the night

Wondering why I smiled.

I just bolded the the sentences which I don't understand

Also, can you just tell me a short and simple meaning/story about what is going on in this poem and what is a poet trying to describe/tell us.