English uses conjugation to indicate simple present and simple past tenses. "I speak" is in the present tense, while "I spoke" is in the past tense. English uses auxiliary verbs to indicate other tenses. Thus "I will speak" is in the future tense, while "I had spoken" and "I have spoken" are in the past perfect and present perfect tenses, respectively. A progressive tense ("I am speaking") can be used to indicate that the action is continuing.
Spanish also uses conjugation as well as auxiliary verbs to form the tenses. Hablo (I speak) is in the simple present, while estoy hablando (I am speaking) is in the present progressive. Spanish has a type of past tense, the imperfect, that doesn't have an exact equivalent in English. For example, hablaba can mean "I spoke" or "I used to speak."
The grammatical tense of a verb doesn't always coincide with the actual time the verb refers to. For example, the simple present tense in both English and Spanish can refer to events of the future. Thus "we leave at 8" and the Spanish equivalent, salimos a las ocho, are both in the present tense but refer to a future event.
