My mother's report says "Mild provocable ischemia noted in apico-anterolateral and mid-anterolateral segment of left ventricle." What does this mean?

Provocable ischemia. means induced poor or lack of blood flow to a particular organ. In this case, a particular area of the heart. Usually occurs when the coronary arteries, the arteries that feed the heart, are clogged or compressed. Typically worsens with exertion, when the arteries are clogged. Reduction in cholesterol & BP by eating healthier helps as well as if serious disease, stent placement to keep flow going.
Arterial blockage. Ischemia in areas of the heart, as you have related, infers that the arteries that feed these parts of the heart are narrowed such that blood flow through them reduces with exertion. It means these areas of the heart are vulnerable and further testing is needed and intervention may be necessary.