Spreadsheet cleanup

Describe the mess, get the formula and the steps.

I have a spreadsheet in {app} and I want to fix this: {problem}

Here are the first few rows exactly as they appear, including the headers:
{sample_rows}

Give me, in this order: (1) what is actually wrong with the data, (2) the formula or the steps to fix it, written for {app}, (3) how I check the fix worked on a row I can see. Do not tell me to use a script unless a formula genuinely cannot do it. If the sample rows are not enough to be sure, say what else you need.