Increasing temperature gives more kinetic energy to both enzyme and substrate so they move more and with more energy. They can then collide more frequently allow more binding so the rate of reaction increases. But beyond the optimum temperature, increasing temperature decreases the rate of enzyme activity as the enzyme is denatured meaning it loses its shape and cannot bind the substrate as it is no longer complementary.
Substrate concentration being increased also increases the enzyme's activity as there is more substrate for the enzyme to bind to. But beyond a point, increasing substrate conc has no effect as the enzyme concentration becomes limiting. This means there is so much substrate that there is not enough enzyme to bind to it at a rate to fully maximise the rate. Increasing enzyme conc would increase rate.