Target top of first page is a bidding strategy if you are focused on the average position of your ads being either position 1 or at the top right hand side of the results.
Your keyword bids will change to ensure you meet the above criteria.
You can cap the bid at a certain amount to ensure the bids don’t get out of control, but if this is done, the position is not guaranteed. The last option is to choose if you decide to raise bids for keywords with a lower quality score, this is dependent on how low the quality score is, but I would suggest if you have keywords with a quality score of 1 or 2 to not enable this option.