Well if you didn't already know, it refers to people living in poverty of sorts. In these days, we'd say someone is "living from pay-check to pay-check" ("check" is also correctly spelt as "cheque").
Now that's what obtains in the world however, the Lord expects us to live from "heart to mouth."
To successfully live from "heart to mouth," we must know and monitor what gets into our heart.
In other words, we must "keep and guard our hearts with all vigilance and above all that we guard, for out of it flow the springs of life."*
In Deuteronomy 11, God's instructions were clear about what should be in our hearts:
18 Place these words on your hearts. Get them deep inside you. Tie them on your hands and foreheads as a reminder. 19 Teach them to your children. Talk about them wherever you are, sitting at home or walking in the street; talk about them from the time you get up in the morning until you fall into bed at night. 20 Inscribe them on the doorposts and gates of your cities 21 so that you’ll live a long time, and your children with you, on the soil that God promised to give your ancestors for as long as there is a sky over the Earth. (The Message, emphasis mine)
We each have to invest time in getting the word of God deep within our hearts and the hearts of our children because "...The mouth speaks the things that are in [overflow from] the heart."**
And what we say, determines what we get in life like Proverbs 18: 20-21 says: "From the fruit of their mouth a person’s stomach is filled; with the harvest of their lips they are satisfied. The tongue has the power of life and death, and those who love it will eat its fruit." (NIV)
For your own benefit takes these verses to heart...and live by them daily
This Book of the Law shall not depart from your mouth, but you shall meditate in it day and night, that you may observe to do according to all that is written in it. For then you will make your way prosperous, and then you will have good success. (Joshua 1:8 - NKJV)
1 Blessed (happy, fortunate, prosperous, and enviable) is the man who walks and lives not in the counsel of the ungodly [following their advice, their plans and purposes], nor stands [submissive and inactive] in the path where sinners walk, nor sits down [to relax and rest] where the scornful [and the mockers] gather. 2 But his delight and desire are in the law of the Lord, and on His law (the precepts, the instructions, the teachings of God) he habitually meditates (ponders and studies) by day and by night. 3 And he shall be like a tree firmly planted [and tended] by the streams of water, ready to bring forth its fruit in its season; its leaf also shall not fade or wither; and everything he does shall prosper [and come to maturity]. (Psalm 1: 1-3 - Amplified)
Then, do one more thing regularly,
"decide and decree a thing, and it shall be established for you;
and the light [of God’s favor] shall shine upon your ways."***
Do you know that you are the first & best prophet to & for yourself? Take that "office" seriously.
Live purposefully and profitably from heart to mouth - you and yours will be blessed as you do.
* Proverbs 4:23 - Amplified, personalized
** Matthew 12:34b - Expanded Bible
*** Job 22:28 - Amplified, personalized