The Japanese non-past tense is the same form you'll find in a dictionary, also known as the plain form. In contrast to English, this single verb form can express multiple ideas that would normally require different tenses or helping verbs.

• 兄(あに)は毎日(まいにち)音楽(おんがく)を聴(き)きます。
  My older brother listens to music every day.
• 私(わたし)は来週(らいしゅう)図書館(としょかん)へ行(い)きます。
  I will go to the library next week.
• 犬(いぬ)は走(はし)る。
  Dogs run.

As shown in the examples, the Japanese non-past form covers what would be three distinct verb forms in English: the present tense (e.g., 'eats', 'drinks'), the future tense (e.g., 'will eat', 'will drink'), and the simple present for general statements (e.g., 'eat', 'drink').

Because this one verb form handles several different meanings, including time-related words in your sentence is often crucial for making the intended tense clear to the listener.

• ケンジは週末(しゅうまつ)勉強(べんきょう)する。
  Kenji studies on weekends.
• マリアは３時(さんじ)に来(く)る。
  Maria will come at 3 o'clock.

When a sentence lacks a specific time marker, it usually conveys a general truth or a statement that is always true.

• 太陽(たいよう)は昇(のぼ)ります。
  The sun rises.

To summarize, the non-past tense is used to talk about three main concepts: habitual actions, future plans, and general truths.