Выражение встречается в следующем контексте:

so what if you did wrong things?
when you knew no better
the thing is to draw a line
and be the best you can at any given time

Заранее спасибо

и, если можно, контекст пошире.

Darling, I don't like it when you say
Bad things about yourself
Oh please don't talk that way
You are so beautiful
I wish you could see what I see

You're an Angel
Angel, just like you always wanted to be
You're an Angel
Angel, just like you always wanted to be

So what if you did wrong things?
When you knew no better
THE THING IS TO DRAW A LINE
And be the best you can at any given time

So what if some don't love you
That just means they do not know your heart
Is like the deepest ocean
Full of kindness and compassion

You're an Angel
Angel, just like you always wanted to be
You're an Angel
Angel, just like you always wanted to be

And I don't want no wedding band
No shiny jewel for my hand
I only want a golden chain
To hang my love upon,
To hang my love upon,
To hang my love upon

Don't hide your eyes from mine
Angels do fall down sometimes
They do get blind
It happens all the time

Oh let your eyes look into mine
You know I loved you all the time
I loved you all the time
Oh how I missed you when you weren't mine

So many tears I cried
Just like a little child
But now those days are gone
I'm by your side
I'll love you even after I die

You're an Angel
Angel, just like you always wanted to be
You're an Angel
Angel, just like you always wanted to be

And I don't want no wedding band
No shiny jewel for my hand
I only want a golden chain
To hang my love upon,
To hang my love upon,
To hang my love upon

единственный кусок, который я здесь не могу понять

Там по смыслу, что когда-то ты делала плохо, но что с того, ты тогда и не знала хорошего. А теперь надо забыть все, что было в прошлом (провести черту между сейчас и тогда) и быть лучшей здесь и сейчас.
Как-то так...