Engine codes run on 2004 Freestar?

I just had engine codes run on my 2004 Freestar because the 'check engine' light has been on. It came back as "Lean Front Bank" and "Lean Rear Bank". What does this mean? This started after I had a hole in the vacuum hose, and my husband replaced it, but the 'check engine' light has not gone off yet, after a few weeks of daily driving.

Make sure you have all the vacuum leaks repaired.
Disconnect the battery for two mins,codes my clear.
The codes you got are O2 Sensors,because of the vacuum leak,which leaned out the readings and set the codes.