by

Used to indicate the proximity of something, the method or means by which something is done, the agent performing an action (especially in passive voice), a point in time or a deadline, or a margin of difference in measurement. It can also indicate the route taken or the mode of transport.

• The small village is located by the sea. — The village is near the sea.
• I sent the package by express mail. — This indicates the method of sending.
• The novel was written by a famous author. — This shows the agent of the action.
• Please submit your report by Friday. — This sets a deadline.
• He earned his living by painting portraits. — This describes the means of livelihood.
• The team won the game by two points. — This indicates the margin of victory.
• We traveled by train across the country. — This specifies the mode of transport.

When 'by' functions as an adverb, it often means 'past', 'near', 'aside', or 'along'. Its meaning is highly contextual and frequently appears in phrasal verbs, or in constructions where it indicates moving past something, being close to something, or putting something aside for later. This usage is often untranslatable into a single Spanish word because Spanish tends to use more specific verbs or adverbial phrases to convey these nuanced meanings (e.g., 'pasar por', 'junto a', 'apartar', 'dejar para más tarde'). It often implies a passing motion or a state of being nearby or set aside.

• She walked by without noticing me. — She walked past me.
• Could you drop by later this evening? — Could you visit or come past later.
• He stood by while I worked on the project. — He remained near or present.
• Let's put that idea by for now and revisit it later. — Let's set that idea aside.
• Time flies by when you're having fun. — Time passes quickly.