The skill of leading a country well — the ability itself, not the person who has it. So statesman is the leader and statesmanship is what they are good at: seeing far ahead, keeping calm in a crisis, getting enemies to agree, putting the country above the party. When a newspaper writes "the talks failed for want of statesmanship", it means nobody in the room had that skill. It is a formal, admiring word, and it takes no a and no plural — you speak of statesmanship, real statesmanship, an act of statesmanship. It also appears in requires statesmanship and a rare piece of statesmanship. Notice what the -ship ending is doing. It makes the name of a skill or a condition that goes with being that kind of person: friend → friendship, leader → leadership, member → membership. Statesmanship is the leadership of a whole country done wisely. Though actually, like statesman itself, the word feels slightly old-fashioned now, and it is used more about the past than the present — writers reach for leadership or diplomacy when writing about people alive today.

政治家風範、治國才能