Difference between one-sided and two-sided p-values

Hello Tess,   We're glad that you reached out.   If the alternative hypothesis is (say for test on one mean) Ha: µ < 50 or Ha: µ > 50 we have one sided test. For Ha: µ > 50 the direction is to the right (right-tailed test). For Ha: µ < 50 the direction is pointing to the left (left-tailed test). On the other hand, the alternative hypothesis Ha: µ ≠ 50 does not specify the direction, towards right or left hence we have two-sided test.   Additionally, for 5% alpha, here are the graphs related to rejection region of one sided and two sided tests.     You may also want to check on https://www.udemy.com/the-data-science-course-complete-data-science-bootcamp/learn/lecture/10772630#questions/5330818 for more detailed explanation of the sides of the test.   Hope this helps. Best,
The 365 Team