Encuentro una ficha bajo la mesa.

Encuentro is the present tense of encontrar for yo: (yo) encuentro = I find / I’m finding.
Spanish often uses the simple present to describe something happening right now, especially for actions that are seen as instant or completed at the moment of speaking (like noticing or finding something).
Estoy encontrando (I am finding) is grammatically possible, but it usually suggests a process in progress (e.g., “I’m in the process of finding…”), which sounds less natural for a quick “Aha—I found it” moment.

Spanish commonly drops subject pronouns because the verb ending already shows who is doing the action.
Encuentro already signals I. You can add yo for emphasis or contrast:

• Yo encuentro una ficha bajo la mesa. = “I find a token under the table (not someone else).”

Ficha has several meanings in Latin America depending on context. Common ones include:

• token / chip (game piece, casino-style token)
• tile (e.g., domino tile)
• card / record card (information card)
• ID tag / badge (in some contexts)
  So una ficha bajo la mesa could be “a token/chip under the table,” but the exact object depends on the situation (game, office, records, etc.).

Una ficha introduces the item as indefinite: “a (some) token.”
You’d use la ficha if it’s specific/known in context:

• Encuentro la ficha bajo la mesa. = “I find the token (the one we were looking for) under the table.”

Both can mean under, but they differ slightly in style and emphasis:

• bajo la mesa = “under the table” (more concise; common)
• debajo de la mesa = “underneath the table” (often a bit more explicit about position)
  In everyday Latin American Spanish, bajo la mesa is very normal.

Yes—Spanish also has the idiom pagar bajo la mesa = “to pay under the table” (off the books).
But in Encuentro una ficha bajo la mesa, it’s strongly read as literal location unless the wider context points to corruption/secret dealings.

Both can mean to find. Generally:

• encontrar is the most common everyday verb.
• hallar can sound more formal or more literary in many places (though it’s common in some regions).
  In this sentence, Encuentro is the neutral, standard choice.

Not here. Encontrar by itself usually means to find.
To mean “to meet (someone),” Spanish typically uses:

• encontrarse con alguien = “to run into / meet up with someone”
  Example: Me encuentro con Ana.
  Since your sentence has an object (una ficha) and a location (bajo la mesa), it clearly means find.

The personal a is used before a specific person, a personified being, or sometimes a pet.
Example: Encuentro a mi amigo.
Here the object is una ficha (a thing), so no personal a is used.

Yes. Spanish word order is flexible, and moving the location phrase can change emphasis:

• Encuentro una ficha bajo la mesa. = neutral
• Bajo la mesa encuentro una ficha. = emphasizes where you found it
• Encuentro bajo la mesa una ficha. = also possible, a bit more “narrative” in tone

Most commonly you’d use the preterite for a completed event:

• Encontré una ficha bajo la mesa. = “I found a token under the table.”
  If you want to describe it as part of background/ongoing past context, you might use the imperfect:
• Encontraba una ficha bajo la mesa (less common; implies a repeated/habitual or ongoing past finding context, usually needs more context)