The word "chingada" is a strong obscenity which is typical of Mexico, where the Pyramid of the Sun is located, as well as in some other Spanish-speaking countries. Someone has suggested that Frida is using the expression to count seconds. However, I believe Frida is not counting seconds. The paragraph itself tells us that she is counting the steps. But she is not only counting them -- she is damning (cursing at) each step as she painfully climbs the pyramid. In English, it would be like saying, "fucking 42, fucking 43..." By the way, to count seconds in English, you can use the "one Mississippi, two Mississippi" method, or you can say, "one, one-thousand, two, one-thousand, three, one-thousand."

Hola, esa expresión es solo utilizada por hablantes de latinoamerica. No es correcto decirlo. La utilizan a la hora de contar, es como decir " mississipi uno, mississipi dos, mississipi tres...". Es para contar mejor el tiempo, los segundas, porque supuestamente al decir "uno" "dos".. tardas menos de un segundo en decirlo, y de esta forma "mississipi uno o una chingada" supuestamente tardas un segundo exacto. No tiene mayor importancia.