Each Hebrew verb also identifies the tense of the verb. In English a verb can have three tenses - past, present or future. Examples of these would be "You cut a tree" (past), "You are cutting a tree" (present) and "You will cut a tree" (future). Biblical Hebrew only has two tenses - perfect and imperfect. While the three verb tenses in English are related to time, Biblical Hebrew verb tenses are related to action. The perfect tense is a completed action while the imperfect tense is an incomplete action.
As we have learned, the verb קצרתי identifies the subject of the verb as first person - "I" but, it also identifies the verb as "perfect tense," a completed action - "I cut." When the verb is written as אקצר the subject of the verb is also first person - "I" but, the tense is now "imperfect tense," an incomplete action and can be translated as "I am cutting a tree" (an action that has begun but not yet completed) or "I will cut a tree" (an action that has not yet begun).
Below is a chart for a few verb conjugations in the perfect and imperfect tense. Notice that when the added letters are at the end of the verb they are in the perfect tense but when they are at the beginning (and maybe at the end as well) they are in the imperfect tense. This can help you easily identify the tense of the verb.
These conjugations are the same for any verb (though there are some exceptions which we will cover in another lesson). The chart below are the same conjugations as the chart above for the verb דבר (dabar) meaning to "speak."
Below is a more detailed chart for all the conjugations for the verb qatsar in the perfect and imperfect tenses. By memorizing the various letters added to the root verb one can easily learn to identify the meaning of a verb. This chart is available in a PDF and Excel Spreadsheet (Hebrew Font required for the excell document). While additional verb forms will be learned in the upcoming lessons, about 90% of the verbs in the Hebrew Bible will use the forms listed in this chart.
The letter "ו (vav) is used as a prefix meaning "and." For instance, the word ועץ (v'ets) means "and a tree." This prefix can also be added to a verb such as in the sentence וקצרתי עץ (uqartsiy ets) which would mean "and I cut a tree." but, because the vav is prefixed to the verb it reverses the tense of the verb so, וקצרתי עץ would actually be "and I will cut a tree" (imperfect tense).
The sentence אקצר עץ (eq'tsar ets) means "I will cut a tree" but ואקצר עץ (ve'e'qatsar ets) means "and I cut a tree."
However, this is not a hard and fast rule. While the letter vav usually reverses the tense of the verb, it is not always the case and only the context of the phrase within the text will determine if the tense is reversed or not.
One other note, the negative particle לֹא (lo) precedes a verb to negate its action such as in the phrase לא קצר יעקב עץ which would be translated as "Jacob did not cut a tree."