Spreadsheets made for people are often wide: one row per region, one column per month. Power BI works best with long tables: one row per region and month, with a single Target column, so a measure can sum it and a slicer can filter the months.
Unpivot turns columns into rows. Select the columns that identify a row (here Region) and choose Transform > Unpivot Columns > Unpivot Other Columns. Every other column becomes two: Attribute (the old header, such as Jan) and Value.
Prefer Unpivot Other Columns. When next year's file adds July, July gets unpivoted too, because the step names only the columns to keep.
Remove totals first. A Total column would be unpivoted into rows labelled Total, and every sum would count the budget twice. Pivot does the reverse, turning rows back into columns.