How does emjambment and additional syllable in poems construct meaning?

1. Why do poets use emjambment (apart from conforming the rhyming scheme)? What meaning can it be constructed through emjambment?
For example: a poem by Elizabeth Barrett Browning- Consolation
Lines 1, 2 are run-on lines.

1. ALL are not taken; there are left behind
2. Living Belovèds, tender looks to bring
3. And make the daylight still a happy thing,
4. And tender voices, to make soft the wind:

2. I've seen in some poems there is one extra syllable added to the last feet in one particular line, is it a way to emphasizing something?

Talking of enjambment reminded me of an Arabic poem where enjambment prevailed . It seems exceptionally nice because it played the role of the binding mortar between the lines of a monolithic sensitive story.

I deliberately used ( she ) for the pigeon to transfer the Arabic atmosphere where that pigeon played the main role.
**
As if my heart when they said
Layla from the town has fled
A pigeon whose wing was caught by a trap on a tree
Struggling all night to set it free
Thinking of her two chickens in the wilderness
Where wind was blowing their nest in a mess
When they heard the wind whistling
Assuming mother came back, to meet her they kept wrestling
Neither she succeeded all that night
Nor in the morning she could achieve a flight
**

Needless to say that the outcome of my effort to achieve rhythm and rhyme is humble.
By I tried to put it in an near as I could to an English verse form .
I hope you like it.

There's a lot of sorrow for that pigeon trapped and unable to get home, khashan.

I think enjambment and extra syllables help to make the poem have a pleasant sound rather than add any particular meaning, but I might be misunderstanding the question, abbyroselou.