The Axe is one of the many tools used for managing your farm in Harvest Moon: Friends of Mineral Town. Depending on the level, it can be used for chopping branches and splitting stumps. You can upgrade your tools by giving the appropriate ore and fee to Saibara at the blacksmith's shop. You can measure your upgrade level in the tools menu. Every 100% is an upgrade and will denote the level you can upgrade to with a miniature ore icon of the appropriate level.