Adding a note to SG's response:
The huge numbers on the Y axis, and the blue line running across the top of the chart appear to be caused by the chart reading the dates in column A as data, converting each date to a serial number counting the days since January 1, 1904, and plotting the data point for the Untitled n category at that height on the graph.
On a Line chart, the category names need to be in a Header column (or Header row). Not having a Header column in the table explains the "Untitled" category labels on the horizontal axis.
When you delete the current Line Chart, and replace it with the suggested x-y scatter chart, using the same two columns of data, the dates will be interpreted as dates and will become the x datum for each pair; the amounts will become the y datum, and the x and y axes will be better scaled to fit the 'unconverted' date data and the unchanged amount data, allowing the viewer to actually perceive the slope of the lines connecting the data points.
Regards,
Barry