The character 建 is rarely used alone in modern spoken Chinese. It almost always combines with other characters to form more specific words.
Physical Construction: This is the most literal meaning. It's used for anything from small houses to massive infrastructure projects.
建房子 (jiàn fángzi): to build a house
建桥 (jiàn qiáo): to build a bridge
建筑 (jiànzhù): architecture, a building (noun)
Establishing Abstract Concepts: 建 is crucial for describing the founding of organizations, systems, and relationships.
建立公司 (jiànlì gōngsī): to establish a company
建立关系 (jiànlì guānxì): to establish a relationship
建国 (jiànguó): to found a country
Making a Suggestion: In the word 建议 (jiànyì), it takes on the meaning of “to propose” or “to put forward.” Literally, it means to “build a proposal.” This is an extremely common usage in daily conversation and business.
Its connotation is almost always neutral or positive, implying progress, stability, and creation. It is used in both formal and informal contexts, though the specific words it forms (like 建设) can be quite formal.