Where to change the name of the project?

This varies by server.

Tomcat

You must change the context root in the project properties. To do this, access the project properties (ALT + ENTER) and select Web Project Settings :

JBoss

For JBoss it is necessary to add the file jboss-web.xml within WEB-INF to the content:

<jboss-web>
    <context-root>PrevisaoVendas</context-root>
</jboss-web>

For other servers I do not know how it works. I always messed with those two just.

Inside the file pom.xml you can find these settings, just modify:

<groupId>br.com.home</groupId>
<artifactId>PrevisaoVendas</artifactId>
<version>1.0</version>
<packaging>war</packaging>
<name>PrevisaoVendas</name>