if you want to access table cell
WebElement thirdCell = driver.findElement(By.Xpath("//table/tbody/tr[2]/td[1]"));
If you want to access nested table cell -
WebElement thirdCell = driver.findElement(By.Xpath("//table/tbody/tr[2]/td[2]"+//table/tbody/tr[1]/td[2]));
For more details visit this Tutorial