There are words in Spanish which change their meaning depending on if they have or do not have a written accent.
Let's look at "tú" vs "tu".
Tú
- Tú is a subject personal pronoun.
- It has a written accent on the u and it is a single word.
- The direct English translation is you (singular informal).
For example:
Tú eres inteligente.You are intelligent. ("You" singular informal) Tu
- Tu is written without an accent on the u.
- It is a possessive adjective.
- The direct English translation is your (singular informal).
For example:
Soy tu madre.I am your mum. ("Your" singular informal)
Here are some more examples:
Tú tienes un perro negro.You have a black dog. ("You" singular informal)
María habla con tu amigo.Maria talks to your friend. ("Your" singular informal)
María habla con tu amigo.Maria talks to your friend. ("Your" singular informal) Tú eres inteligente.You are intelligent. ("You" singular informal) Soy tu madre.I am your mum. ("Your" singular informal) Tú tienes un perro negro.You have a black dog. ("You" singular informal) 
